Limb amputation and limb deficiency: epidemiology and recent trends in the United States.

ABSTRACT

Background. The purpose of this study was to provide a comprehensive perspective on the epidemiology and time trends in the incidence of limb amputations and limb deficiency in the United States.

Methods. Data from the Healthcare Cost and Utilization Project from 1988 through 1996 were used to calculate rates of congenital deficiency, trauma-related, cancer-related, and dysvascular amputations in the United States. Trends over time in adjusted rates were then examined using linear regression techniques.

Results. Dysvascular amputations accounted for 82% of limb loss discharges and increased over the period studied. Over all years, the estimated increase in the rate of dysvascular amputations was 27%. Rates of trauma-related and cancer-related amputations both declined by approximately half. The incidence of congenital deficiencies remained stable.

Conclusions. The risk of amputations increased with age for all causes and was highest among blacks having dysvascular amputations. Increasing risk of dysvascular amputations, particularly among elderly and minority populations, is of concern and warrants further investigation.

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LIMB LOSS is a potentially devastating event in a person's life, often resulting in profound physical, psychologic, and vocational consequences. Despite the potential adverse impact of partial loss, total loss, or deficiency on everyday function and quality of life, precise figures on the incidence of limb loss and limb deficiency are not currently available. For the most part, existing estimates for the United States are based on cross-sectional state-level analyses, with specific focus on a given etiology (in particular, dysvascular limb loss due to diabetes) (1-12) The single nationally-representative, population-based study of trends in amputation rates in the United States focused exclusively on major lower-extremity amputations (ie, amputations at the transfemoral, transtibial, and through-foot levels) due to peripheral vascular disease. (13)

Although limb loss due to such dysvascular causes represents a large share of overall amputations, a number of alternative pathways--most notably, trauma, malignancy, and birth anomalies--may lead to limb loss. In contrast to dysvascular amputations, investigations into the incidence of trauma-related and malignancy-related limb loss, as well as congenital limb deficiencies, have been few, with most conducted outside of the United States. (14-32) Estimates reported in these studies, including those focusing on dysvascular amputations, tend to vary widely because of the nature and composition of the sample, as well as differences in definitions of limb loss and limb deficiency.

The purpose of this study was to provide a comprehensive perspective on limb loss and limb deficiency in the United States. The incidence rates and time trends in limb amputations and limb deficiencies by etiology and level of amputation were examined using nationally representative hospital discharge data from 1988 to 1996. Understanding the magnitude and trajectory of limb loss and limb deficiency in the United States represents an important first step in the development of targeted clinical and policy interventions.

MATERIALS AND METHODS

Data Sources

Data from the Healthcare Cost and Utilization Project, Nationwide Inpatient Sample (HCUP-NIS) from 1988 through 1996 were used to develop estimates of limb-loss and limb-deficiency incidence rates in the United States. The HCUP-NIS, a component of the Agency for Healthcare Research and Quality (AHRQ) Healthcare Cost and Utilization Project (HCUP3), is a stratified probability sample designed to approximate a 20% nationwide sample of community, nonfederal, short-term hospitals. Excluded from the database are admissions to federal hospitals, psychiatric hospitals, and substance-abuse treatment facilities. The HCUP-NIS contains discharge abstracts for all stays in the sampled hospitals, which total approximately 6.5 million records annually. Data for the 1988-1992 HCUP-NIS were drawn from a sampling frame that included hospitals in 11 states; by 1996, the sampling frame had expanded to encompass hospitals in 19 states. For all years, hospital-specific weights were developed to obtain national estimates of hospit al and discharge parameters.

Data abstracted for each hospital discharge include patient demographics, a principal diagnosis and up to 14 secondary diagnoses coded using the Clinical Modification of the 9th Revision of the International Classification of Diseases (ICD9-CM), a primary procedure and up to 14 secondary procedures, length of hospital stay, discharge status and destination, and expected primary source of payment for the hospital charges.

Study Population and Definitions

As a first step, an algorithm was developed to select all patients discharged from acute-care hospitals nationwide between 1988 and 1996 who had either an amputation-related procedure or a limb-deficiency-related diagnosis (referred to as limb-loss-related discharges). Specifically, the initial study population consisted of discharges with (1) a procedure code for upper-limb or lower-limb amputation (ICD-9CM 84.00-84.09, 84.10-84.19, or 84.91); (2) a diagnosis code of traumatic amputation (ICD-9CM 885.0-887.7 or 895.0-897.7); or (3) a diagnosis code identifying congenital deformities of the limbs (ICD-9CM 755.2-755.4).

All limb-loss-related discharges were then classified hierarchically into mutually exclusive categories according to etiology as (1) trauma-related (ICD 810-839, 880-884, 885-887.7, 895-897.7, 925-929, 942-949, or 958-959); (2) congenital deficiency (newborn discharge designation in combination with a congential reduction anomaly ICD 755.2-755.29, 755.3-755.39, or 755.4); (3) cancer-related (ICD 170.4-170.8, 171.2-171.3, or 172.6-172.7); (4) dysvascular (ICD 040.0, 250.0-250.9, 440.0-440.9, 442.0442.9, 443.0-443.9, 444.0-444.9, 682.0-682.9, 686.0 -686.9, 707.0-707.9, 728.86, 730.0-730.9, or 785.0-785.9); or (5) other etiology. Records grouped in the "other etiology" category were then examined in depth. Whenever appropriate, records were reclassified into 1 of the 4 main groups, and our classification algorithm was refined to better reflect the etiology of limb loss. For example, discharges with a cause of injury (E-code) related to trauma, such as "late effects of accident" or "injury to blood vessel," were moved into the trauma-related category. The refinement of our classification algorithm continued until records could no longer be categorized into one of the more specific groups. The final category of "other etiology," which contained less than 2% of the sample, primarily included discharges for amputations due to complications of procedures, internal derangement of joints, and other joint disorders. These unclassified discharges were excluded from analyses.

An important part of our effort was the identification of discharges that were presumed to be new or incident cases of limb deficiency and amputation. For instance, discharges that were for rehabilitation (V57.0-V57.9) or reattachment of extremity (ICD 84.21-84.29) were excluded from our analysis of incidence. Discharge records of non-newborn patients that had a code indicative of limb deficiency but no other limb-loss-related diagnosis and no limb-loss-related procedure codes, were also excluded, since it was most likely that these discharges did not identify new cases of limb deficiency, but rather individuals for whom the congenital limb deficiency was included as a comorbid diagnosis. New cases of congenital deficiency, therefore, were identified based on a diagnosis of limb deficiency combined with a newborn code noted in the record for that admission.

Etiology-specific limb-loss-related discharges were further classified into mutually exclusive categories according to the level of the amputation. Lower-limb levels for dysvascular, trauma-related, and cancer-related amputations were classified as toe(s), foot, ankle, transtibial (below-knee), through-knee, transfemoral (above-knee), hip disarticulation, and pelvic. Upper-limb amputations were classified as thumb, finger(s), hand, wrist, transradial, through-elbow, transhumeral, shoulder, and forequarter amputation levels. With the exception of trauma-related discharges for which specific codes for bilateral upper or bilateral lower limb amputations were available, whenever 2 amputation procedures were done during the same hospitalization, the most proximal level of amputation was chosen for classification. Discharges involving upper-limb congenital deficiencies were classified according to type and level into transverse, longitudinal hand, longitudinal radial, and longitudinal humeral. Lower-limb congenital deficiencies were classified as transverse, longitudinal toe, longitudinal foot, longitudinal fibular, longitudinal tibial, and longitudinal femoral. As with amputation levels, limb-deficiency types were classified into mutually exclusive categories, with lower-limb anomalies hierarchically superceding upper-limb anomalies whenever multiple deficiencies were identified during a single discharge with the newborn designation. Multiplelimb anomalies were identified when they occurred, however.

DATA ANALYSIS

Crude population-based rates of limb loss and limb deficiency by age, sex, and geographic region were calculated separately by etiology for 1988 through 1996 using national population data for each year obtained from the US Bureau of the Census and the National Center for Health Statistics. (33-35) Adjusted rates of limb loss and limb deficiency for each year were then calculated using the 1988 US population as the reference to net Out any changes in the population composition over the 9-year study period. Trends over time in adjusted rates were examined using linear regression techniques. Overall patterns in discharge rates by etiology, age, sex, and race were further examined using annual rates for the most recent year in the series (1996). Finally, relative risks by etiology were contrasted across different sex and racial groups (defined as black/African American and nonblack/primarily white) using univariate test statistics. For all analyses, standard errors (SE) and confidence intervals (CIs) that accoun ted for HCUP-NIS's complex survey design were calculated using the STATA 6.0 software package (Stata Corp. College Station, Tex).

RESULTS

Trends in Limb Loss and Limb Deficiency

A total of 1,199,111 hospital discharges involved limb loss or limb deficiency in the United States over the 9-year period between 1988 and 1996, yielding an average of 133,235 limb-loss-related discharges per year. Rates of limb loss varied substantially by etiology. Amputations due to vascular conditions accounted for the vast majority (82%) of limb-loss discharges and increased from 38.30 per 100,000 persons in 1988 to 46.19 per 100,000 persons in 1996 (Table 1). Trauma-related amputations, the second most common cause of limb loss, declined in rate from 11.37 per 100,000 persons in 1988 to 5.86 per 100,000 persons in 1996 (Table 1). Limb loss due to malignancy, a comparatively rare etiology, showed a marked decrease over this period, from 0.62 per 100,000 persons in 1988 to 0.35 per 100,000 persons in 1996. Finally, the incidence of congenital deficiencies, which accounted for only 0.8% of all limb-loss-related discharges, remained relatively stable over the study period; the rate was 25.64 per 100,000 live births in 1996.

Linear regressions fitted to these data revealed a 3% average annual rate of increase in total discharges for dysvascular amputations, and 5.6% and 4.7% average annual rates of decrease for trauma-related and cancer-related amputations, respectively. These rates of change were statistically significant (P < .01). Over the 9-year period, the estimated increase in the rate of dysvascular amputations was 27%. The overall decreases in rates of trauma-related and cancer-related limb loss were estimated at 50.2% and 42.6%, respectively.

Limb Loss by Etiology and Level

Lower-limb amputations accounted for 97% of all dysvascular limb-loss discharges, with an increase in rate per 100,000 persons from 36.99 in 1988 to 44.92 in 1996 (Table 2). More than half (53.6%) of all dysvascular amputations were at the transfemoral (above-knee) or transtibial (below-knee) levels (25.8% and 27.6%, respectively), while 31% involved the toe(s). Annual rates by level suggested an upward trend in the incidence of dysvascular amputations for most levels. Increases were particularly noticeable among levels associated with considerable functional impairments, such as foot (increasing from 3.5 per 100,000 in 1988 to 5.75 per 100,000 in 1996), transtibial (from 10.9 to 12.3 per 100,000), and transfemoral amputations (from 10.6 to 11.9 per 100,000) (Table 2).

In contrast to dysvascular amputations, which primarily involved lower extremities, upper-limb amputations accounted for the vast majority (68.6%) of all trauma-related amputations occurring during the study period (Table 2). More than half of all trauma-related amputations and three quarters of all upper-limb traumatic amputations occurred at the lowest (finger) level (Table 2). With a few exceptions (through-knee, pelvic, wrist, transradial, and shoulder amputations), incidence rates were lower in 1996 relative to 1988, with the most marked reduction occurring in the incidence of hand amputations (declining from 0.07 per 100,000 persons in 1988 to 0.02 per 100,000 persons in 1996).

Limb amputations resulting from malignancy most commonly involved the lower limb; transfemoral (above-knee) and transtibial (below-knee) amputations alone accounted for more than a third (36%) of all cancer-related amputations. For almost all levels, however, rates of amputation due to cancer declined over the study period (Table 2).

Table 3 presents the numbers and rates per 100,000 live births of limb deficiencies, by level, for the group of newborns identified with congenital reduction defects. Congenital deficiencies of the upper limb were most common and accounted for 58.5% of all newborn limb-deficiency discharges. Among those, longitudinal hand reductions were most frequent, accounting for 46.4% of upper-limb anomalies (Table 3). Longitudinal toe reductions were the most common finding among newborns with lower-limb deficiencies. Overall, multiple congenital limb reductions were identified in 17.8% of these infants.

Relative Risk of Limb Loss and Limb Deficiency by Etiology, Sex, and Race

Age-specific rates of dysvascular, trauma-related, and cancer-related amputations for the most recent year in the series (1996) by sex and race are summarized in Table 4. Incidence rates of dysvascular amputations increased dramatically with age in both sexes and in both racial groups. The pattern of increase by age, however, was particularly striking among women and blacks; the risk of a dysvascular amputation among blacks aged 85 or older, for example, was 11.7 times (95% CI, 11.1-12.3) than of their middle-aged (aged 45-54 years) counterparts (1057.8 per 100,000 persons compared with 90.4 per 100,000 persons). Although significantly lower in magnitude, incidence rates for women in the same age groups yielded a similar risk ratio of 12.0 (95% CI, 11.6-12.5), with rates of 351.8 per 100,000 persons for older women versus 29.2 per 100,000 persons for middle-aged women. Similar figures for men and nonbiacks indicated risk ratios only two thirds as large at 8.2 (95% CI, 7.9-8.5) and 8.7 (95% CI, 8.5-8.9) times higher for men and nonblacks, respectively. In all age groups, the risk of dysvascular amputation was highest among blacks. Differences were most pronounced, however, for the older cohorts. Racial differences in relative risk increased from twofold among younger age groups (aged 44 or younger) to more than threefold among the oldest old. Overall, the male-to-female risk ratio of dysvascular amputations was 1.75 (95% CI, 1.74-1.76).

Males were also at significantly higher risk of trauma-related amputations than females, with an incidence rate ratio of 4.94 (95% CI, 4.934.95). For both males and females, risk of traumatic amputations increased steadily with age, reaching its highest level among those aged 85 and older (16.3 per 100,000 males and 10.4 per 100,000 females). The pattern of incidence by age differed slightly for blacks and nonblacks; however, blacks, particularly those aged 35 and older, were generally at a higher risk than non-blacks for trauma-related amputations. Among nonblacks, incidence of trauma-related amputtions was essentially constant across age groups, at about 7 per 100,000, except for a much lower rate at younger ages (1.8 per 100,000 for those aged 0-14) and a higher rate among older ages (9.5 per 100,000 persons among those aged 7584 and 11.9 per 100,000 persons among those aged 85 and older).

Finally, there were no notable differences by sex or race in the age-specific risk of cancer-related amputations, though rates of limb loss due to cancer were generally higher among nonblacks.

DISCUSSION

This study used nationally-representative hospital discharge data to provide a comprehensive view of limb loss and limb deficiency in the United States. The analysis differs from related work in 3 important respects: (1) its focus is on a nationwide population; (2) unlike most previous research that examined incidence of dysvascular amputations among persons with diabetes, (1,2,5-11) we examined limb loss across a broad group of etiologies; and (3) a distinctive feature of the study is the explicit focus on time trends, including analyses by level of amputation.

Our findings reveal striking differences by etiology in the rate of limb loss, in 1996, the rate of dysvascular amputations was almost 8 times greater than that of trauma-related amputations, the second-leading cause of limb loss. Amputations due to malignancy occurred at significantly lower rates (0.35 per 100,000 persons in 1996).

In contrast to declining rates of trauma-related and cancer-related amputations, we found evidence of a significant increase in the incidence of dysvascular amputations. Regression techniques applied to yearly age-standardized and sex-standardized incidence rates indicated a 27% (P < .001) estimated increase in amputations due to vascular conditions over the 9-year study period. During the same period, rates of trauma-related and cancer-related amputations decreased 50% and 43%, respectively, while rates of congenital anomalies among newborn discharges remained virtually unchanged at 26 per 100,000 live births.

Overall, the risk of amputations increased with age. This was true for all etiologies and for both racial groups and both sexes, though the rate of increase was especially high among blacks having dysvascular amputations. About 1 of every 100 blacks aged 85 or older had an amputation due to vascular disease in 1996. Men were also generally at higher risk for limb loss than women, with the pattern being particularly notable in trauma-related amputations. The finding of a higher male-to-female ratio in dysvascular and trauma-related amputation rates is consistent with results reported in a number of other studies. (3,4,9,15,36-40)

Although a similar pattern was not evident in the incidence of traumatic, malignant or congenital-deficiency limb loss, there were marked differences by race in the incidence of amputations due to vascular conditions. Whereas slightly more than 12% of the 1996 US population reported being black, blacks accounted for nearly a quarter of all dysvascular amputations in that year. Studies focusing on persons undergoing amputations due to diabetes generally report similar racial differences. (1,4,7)

Findings of a relatively high and increasing rate of dysvascular amputations are consistent with results reported in other studies. (3,12-16,29,36-38) Using biannual data from the National Hospital Discharge Data Survey (NHDS) for 1979-1980 to 1995-1996, Feinglass et al (13) noted that the incidence of major dysvascular amputations (ie, amputations at the foot, below-knee, and above-knee levels) increased by 10.6% between the 2 periods. Our results, based on analyses that included only amputations at those 3 levels for comparability, revealed a 19.5% rate of increase in such major amputations between 1988 and 1996. The difference in the rate of increase in major dysvascular amputations across the 2 studies may reflect underlying differences in sample design, coding schemes, and populations covered by the HCUP-NIS and the NHDS. Of note, the HCUP-NIS is restricted to states that maintain statewide, all-payer, discharge-data files, while the NHDS uses an unrestricted sampling frame. In addition, contrary to HCUP 's stratified probability sample of acute-care, general-specialty, community hospitals, the NHDS includes in its frame a small number of specialty hospitals, such as psychiatric, maternity, orthopedic, and head-injury facilities.

Many factors may have contributed to the observed increase in the incidence of amputations due to vascular diseases. Increased prevalences of diabetes, smoking, hypertension, and hypercholesterolemia--important risk factors for peripheral vascular disease and amputation--which have been documented in recent studies may explain these findings. (41, 42) Changes in clinical management and health-care delivery may also be contributing to the increasing rates of dysvascular amputations.

The pronounced downward trend in the risk of trauma-related amputations may also be attributed to several causes. Changes in the aggressiveness of both reconstructive (limb-salvage) surgery and reimplantation of severed digits may account for part of the decline in trauma-related amputation rates. The decline may also represent an actual decrease in incidence of injuries severe enough to result in amputation. Improved occupational safety standards, as well as increased awareness and enforcement of overall safety regulations, may have led to a decline in the incidence of injurious events or to a decrease in the severity of injuries sustained. This hypothesis is supported by studies of the effectiveness of interventions aimed at reducing workplace risks, as well as the effectiveness of prevention programs targeted at the general population. (43, 44) The decline in incidence of minor traumatic amputations (ie, those at the finger or toe levels), however, may be an artifact of the data used in the analysis. Becau se our analysis is based on hospital discharges, it is possible that the decline reflects a change in medical practices concerning hospital admission for relatively minor amputations. If finger and toe amputations were less likely to warrant a hospital admission in 1996 relative to 1988, then reported rates based on hospital discharges underestimate the true incidence rate of minor trauma-related amputations.

In addition to providing new insights into the epidemiology and characteristics of dysvascular and trauma-related amputations, this study presents the first estimates of rates of limb loss due to malignancy and congenital deficiencies in the United States. Previous analyses documenting malignancy-related amputations--all of which were conducted in other countries--report cancer as the reason for limb loss in 2% to 5% of all amputations, a proportion significantly higher than the 0.9% found in this study (population-based rates not reported in the other studies) . (11, 14, 29, 36, 45, 46) It is unclear to what extent these differences reflect differences in methodology across studies, true differences in the relative rate of amputations due to cancer, or both. For the purpose of this analysis, amputations were classified as cancer-related whenever a discharge record included both an ICD9CM procedure code for amputation and an ICD9-CM code of an upper-extremity or lowerextremity malignancy. Although unlikely, g iven our hierarchical approach to classifying etiology and the absence of codes suggesting other causes, it is possible that the limb malignancy was not the primary reason for amputation. However, our consistent methodology for coding cancer-related amputations ensured that our findings regarding time trends were unbiased. In fact, recent studies indicate a trend toward more aggressive use of limb-sparing procedures for management of osteosarcomas, suggesting that change in medical practice may largely account for the observed decline in the incidence of limb loss due to malignancies.

Another source of limb loss that has received little attention in the literature is congenital limb deficiencies. (21, 23-25) The incidence reported here of 26 per 100,000 live births is about half that reported by Froster et al (23-26) (who reported 60 per 100,000 live births) using data from British Columbia. In a study using the Swedish Registry of Congenital Malformations, Kallen et al (27) reported a rate of 62.5 per 100,000 live births. Higher rates of about 50 per 100,000 live births have also been reported in studies using data from Finland and Hungary, (20, 22, 28) Comparisons across studies are hindered, however, by inherent cross-country differences in diagnosis definitions, nomenclature, and data sources. Kallen et al, (27) for example, remarked on the limitations of using ICD9-CM codes for describing congenital limb deficiencies, and noted the strength of the Swedish registry, in which special data cards are completed by physicians and catalogued under a central surveillance system.

Despite differences in rates, a number of similarities were evident across studies. Consistent with findings documented here, Kallen et al (27) observed a slight male preponderance in the incidence of limb reductions. Froster-Iskenius and Baird (23) also reported a higher proportion of upper-limb (as opposed to lower-limb) reductions among newborns with limb deficiencies.

Hospital discharge data provide a unique opportunity to examine incidence rates in a general population, but certain inherent limitations to analyses use such administrative data. One important constraint is the absence of specific ICD9-CM codes with which to identify dysvascular amputations. Dysvascular amputations are often the final common sequelae in a variety of clinical pathways. The development of a nonhealing foot ulcer due to poor circulation, for example, often results in limb amputation. Severe, unremitting, vascular limb pain may also require amputation. Cellulitis in a foot with limited blood supply, a potentially life-threatening condition, may also prompt a limb amputation, as may acute arterial thrombosis or overwhelming sepsis that results in distal limb infarction. Development of more specific ICD9-CM codes for amputations resulting from vascular disease, though a difficult task, would further research and public policy efforts to more accurately identify these amputations. A similar issue a rises when identifying cancer-related amputations. Finally, arid perhaps most importantly, the unit of observation in national hospital-discharge data such as the HCUP-NIS is the discharge rather than the person. The absence of unique patient identifiers in these data preclude identification of individuals over the course of multiple admissions. As a consequence, to the extent that persons might undergo multiple amputations within a given year, the rates reported here may overestimate the true incidence of limb loss.

CONCLUSIONS

This study examined patterns and trends in the incidence of limb amputations and limb deficiencies by etiology. It provided valuable information regarding age, sex, and race differences in the risk of limb loss, along with insights into recent trends. This study also increased our understanding of congenital limb deficiencies and amputations from cancerous causes; the epidemiology of these conditions has not been well documented. Increasing risk of dysvascular limb loss, particularly among elderly and minority populations, is of concern and warrants further investigation into its causes and consequences.

TABLE 1

Adjusted Annual Rates of Limb Loss and Limb Deficiency Per 100,000 US
Population: 1988-1996

                                         Etiology

                  Congenital *         Cancer              Trauma
Caldenar Year    n = 9,326 (0.8)  n = 10,967 (0.9%)  n = 196,026 (16.4%)

1988                  24.21             0.62               11.37
1989                  19.44             0.51               11.48
1990                  27.26             0.50               10.85
1991                  26.12             0.58                8.73
1992                  26.55             0.56                8.14
1993                  23.79             0.52                6.90
1994                  30.94             0.39                6.85
1995                  29.08             0.31                6.62
1996                  25.64             0.35                5.86
Change over            NS             -42.6% **           -50.2% **
 study period +

                       Etiology

                     Dysvascular
Caldenar Year    n = 982,792 (82.0%)

1988                    38.30
1989                    38.22
1990                    38.89
1991                    38.61
1992                    40.19
1993                    43.52
1994                    45.51
1995                    46.42
1996                    46.19
Change over             26.9% **
 study period +

* Rates per 100,000 live births.

+ Based on linear regression models.

** P < .01.

NS = Not statistically significant.

All rates are standardized to the 1988 US population by age, sex, and
geographic region.
TABLE 2

Numbers and Adjusted Rates of Limb Loss by Etiology and Level

                                      Dysvascular

                          No. (%)           Annual Incidence
Level                    1988-1996            1988   1996

Lower limb (total)      953,367 (97)          36.99  44.92
  Toe                   309,589 (31.5)        11.26  14.42
  Foot                  102,872 (10.5)         3.50   5.70
  Ankle                   7,478 (0.8)          0.40   0.30
  Transtibial           271,550 (27.6)        10.92  12.29
  Through-knee            4,237 (0.4)          0.17   0.17
  Transfemoral          253,145 (25.8)        10.56  11.86
  Hip disarticulation     3,554 (0.4)          0.17   0.16
  Pelvic                    469 (0.1)          0.01   0.02
  Bilateral                   0 (0)            0.00   0.00
Upper limb (total)       29,426 (3)            1.27   1.26
  Thumb                   2,344 (0.2)          0.16   0.08
  Finger(s)              21,427 (2.2)          0.91   0.93
  Hand                    1,255 (0.1)          0.06   0.07
  Wrist                     514 (0.1)          0.02   0.02
  Transradial             1,626 (0.2)          0.05   0.05
  Through-elbow             385 (0.04)         0.01   0.01
  Transhumeral            1,511 (0.2)          0.05   0.08
  Shoulder                  236 (0.02)         0.01   0.01
  Bilateral                   0 (0)            0.00   0.00
  Forequarter               132 (0.01)         0.00   0.007

    Total               982,792 (100)         38.30  46.19

                                   Trauma-Related

                          No. (%)         Annual Incidence
Level                    1988-1996      1988     1996

Lower limb (total)      61,605 (31)     3.21     2.07
  Toe                   27,233 (13.9)   1.41     0.86
  Foot                   4,483 (2.3)    0.22     0.16
  Ankle                    823 (0.4)    0.05     0.04
  Transtibial           14,244 (7.3)    0.78     0.51
  Through-knee             921 (0.5)    0.02     0.04
  Transfemoral          10,821 (5.5)    0.59     0.40
  Hip disarticulation      418 (0.2)    0.04     0.01
  Pelvic                    52 (0.03)   0.00     0.00
  Bilateral              1,504 (0.8)    0.09     0.05
Upper limb (total)     134,421 (68.6)   8.13     3.76
  Thumb                 24,325 (12.4)   1.51     0.62
  Finger(s)            100,316 (51.2)   6.17     2.82
  Hand                     983 (0.5)    0.07     0.02
  Wrist                    415 (0.2)    0.01     0.02
  Transradial            4,001 (2.0)    0.14     0.16
  Through-elbow            346 (0.2)    0.01     0.01
  Transhumeral           3,008 (1.5)    0.17     0.10
  Shoulder                 154 (0.1)    0.00     0.00
  Bilateral                462 (0.2)    0.03     0.00
  Forequarter               15 (0.01)   0.00     0.00

    Total              196,026 (100)    11.37    5.86

                                  Cancer-Related

                         No. (%)         Annual Incidence
Level                   1988-1996      1988     1996

Lower limb (total)      8,351 (76.1)   0.48      0.24
  Toe                   1,466 (13.4)   0.09      0.05
  Foot                    482 (4.4)    0.03      0.02
  Ankle                   164 (1.5)    0.00      0.01
  Transtibial           1,501 (13.7)   0.08      0.05
  Through-knee            133 (1.2)    0.01      0.00
  Transfemoral          2,499 (22.8)   0.16      0.07
  Hip disarticulation     726 (6.6)    0.04      0.02
  Pelvic                1,369 (12.5)   0.07      0.02
  Bilateral                 0 (0)      0.00      0.00
Upper limb (total)      2,617 (23.9)   0.15      0.09
  Thumb                   352 (3.2)    0.03      0.00
  Finger(s)               529 (4.8)    0.04      0.02
  Hand                     92 (0.8)    0.00      0.00
  Wrist                    21 (0.2)    0.00      0.002
  Transradial             212 (1.9)    0.01      0.01
  Through-elbow           123 (1.1)    0.00      0.01
  Transhumeral            488 (4.4)    0.04      0.02
  Shoulder                365 (3.3)    0.01      0.01
  Bilateral                 0 (0)      0.00      0.00
  Forequarter             439 (4)      0.02      0.02

    Total              10,967 (100)    0.62      0.35

Incidence rates per 100,000 US population.

1996 rates are standardized to the 1988 US population by age, sex, and
geographic region.

Totals represent all persons from 1988 to 1996.
TABLE 3

Number and Adjusted Rates of Newborn Discharges With Congenital
Deficiencies by Level

                                          Adjusted Annual Incidence
                           No. (%)         per 100,00 Live Births
Level                     1988-1996    1988               1996

Upper limb (all)        5,458 (58.5)   14.73              15.74
  Transverse            1,398 (15.0)    3.82               3.44
  Longitudinal hand     2,532 (27.2)    6.50               7.68
  Longitudinal radial     641 (6.9)     2.32               1.81
  Longitudinal humeral    104 (1.1)     0.18               0.09
  Unspecified             735 (7.9)     1.78               2.71
Lower limb (all)        3,868 (41.5)    9.48               9.90
  Transverse              457 (4.9)     0.73               1.01
  Longitudinal toe      1,327 (14.2)    3.62               3.47
  Longitudinal foot        67 (0.7)     0.25               0.24
  Longitudinal fibular    178 (1.9)     0.14               0.44
  Longitudinal tibial     158 (1.7)     0.57               0.42
  Longitudinal remoral    568 (6.1)     1.32               1.80
  Unspecified           1,115 (12.0)    2.84               2.52
All discharges          9,326 (100.0)  24.21              25.64

1996 rates are standardized to the 1988 US population by sex and
geographic region. Totals represent all discharges from 1988 to 1996.
TABLE 4

Age-Specific, Race-specific, and Sex-Specific Incidence Rates for Limb
Loss and Limb Deficiencies by by Etiology, 1996

                                           Etiology

                                          Dysvascular

                                        Race                Sex

Age (yrs)                     Nonblack        Black    Male

 0-14                           0.3              1.1     0.5
15-24                           0.8              2.3     1.3
25-34                           3.7              9.1     5.9
35-14                          12.3             30.3    20.1
45-54                          39.0             90.4    60.3
55-64                          94.8            246.7   147.2
65-74                         168.5            417.5   252.4
75-84                         243.3            650.8   372.6
[greater than or equal to]85  338.5          1,057.8   495.6

                                              Etiology

                              Dysvascula          Trauma-Related
                                  r

                                 Sex              Race              Sex

Age (yrs)                     Female    Nonblack   Black     Male

 0-14                           4.0        1.8      2.6       3.8
15-24                           0.7        6.0      5.6      10.3
25-34                           2.9        6.5      5.7      10.9
35-14                           9.0        7.1      7.4      12.2
45-54                          29.2        7.1      8.8      11.9
55-64                          76.5        7.2     10.2      12.6
65-74                         140.3        7.3      8.5      12.1
75-84                         209.4        9.5      8.7      13.9
[greater than or equal to]85  351.8       11.9     14.7      16.3

                                              Etiology

                              Trauma-Rel          Cancer-Related
                                 ated

                                 Sex              Race              Sex

Age (yrs)                     Female    Nonblack   Black     Male

 0-14                          1.5         0.2      0.1       0.1
15-24                          1.4         0.2      0.3       0.3
25-34                          1.9         0.2      0.1       0.4
35-14                          2.2         0.3      0.1       0.3
45-54                          2.9         0.3      0.0       0.3
55-64                          2.9         0.6      0.3       0.6
65-74                          3.7         0.8      0.7       0.8
75-84                          6.6         1.0      0.0       0.6
[greater than or equal to]85  10.4         2.5      1.2       1.2

                               Etiology

                              Cancer-Rel
                                 ated

                                 Sex

Age (yrs)                     Female

 0-14                          0.2
15-24                          0.1
25-34                          0.1
35-14                          0.2
45-54                          0.2
55-64                          0.5
65-74                          0.8
75-84                          1.2
[greater than or equal to]85   3.0

Acknowledgements. We thank Mathilde Sector, MPH, for assistance with evaluation and compilation of the literature; Patti L. Ephram, MPH, for reviewing the manuscript; and David Harville, MS, for programming support.

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RELATED ARTICLE: KEY POINTS

* In 1996, the rate of dysvascular amputations was almost 8 times greater than the rate of trauma-related amputations, the second leading cause of limb loss.

* There has been a significant increase (27%) in the incidence of dysvascular amputations; in contrast, trauma-related and cancer-related amputations have decreased by approximately half, and the rate of congenital anomalies has remained virtually unchanged.

* Risk of amputation increases with age, regardless of etiology, sex, and race; however the rate of increase is especially high among blacks having dysvascular amputations.

* Men are at higher risk than women for limb loss, especially with regard to trama-related amputations.

From the Departments of Physical Medicine and Rehabilitation and Emergency Medicine, School of Medicine, and the Center for Injury Research and Policy, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, Md.

Supported by grant No. U59/CCU416733 from the Centers for Disease Control and Prevention.

Reprint requests to Timothy R. Dillingham, MD, 10352 Waverly Woods Drive, Ellicott City, MD, 21042-1666.