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An analysis of chronic kidney disease risk factors in a Louisiana nursing home population: a cross-sectional study.

INTRODUCTION

Chronic kidney disease (CKD) is a medical condition that has important implications for the management of older people of all ethnic groups. CKD is frequently associated with chronic conditions and risk factors, especially in vulnerable patient populations such as nursing home residents. (1) CKD is common in non-institutionalized older people (approximately 30%), but little is known about the prevalence of CKD amongst people living in residential care. (3) The National Health and Nutrition Examination Survey (NHANES) IV (1998-2004) estimated that approximately 38% of the non-institutionalized US population aged 70 years or older has CKD, defined as an estimated glomerular filtration rate (eGFR) of less than 60 mL/min/1.73[m.sup.2]. (4) Earlier studies assessed the effects of aging by utilizing cross-sectional studies and institutionalized elderly subjects; these studies showed a decrease in renal reserve, along with constraints on the kidney's ability to respond appropriately to challenges of either internal and/or external excesses or deficits. (2) Elderly individuals with CKD have high rates of comorbid conditions, including cardiovascular disease and its risk factors chronic obstructive pulmonary disease (COPD), peripheral vascular disease (PVD), dementia, and dyslipidemia. Therefore, based on the fact that aging is a major CKD risk factor and institutionalized patients have a higher number of co-morbidities, it appears that CKD and its progression appear to be more prevalent compared to that of elderly community dwellers. (5) Moreover, elderly nursing home patients have a higher prevalence of biochemical abnormalities, which, in conjunction with lack of awareness or knowledge of risk factors associated with CKD, put them at risk for CKD and progression. (6,7)

Some risk factors have been associated with the development of CKD in the community. Hypertension, diabetes mellitus, and multiple medications are strongly related to CKD in elderly nursing home residents. (8) Although the prevalence and risk factors associated with CKD in the nursing home setting have not been examined in-depth, (9) the objective of this study is to determine the prevalence of CKD and its associated risk factors on a patient population living in an academic-affiliated nursing home.

METHODS

A cross-sectional study was conducted in a nursing home population of 103 individuals. Medical charts were reviewed, and data was abstracted using standardized forms. Demographics, laboratory tests, current medications, and history of diagnoses were abstracted. Electronic files were generated, and data were analyzed using SAS 9.2 software. Chi square and t-test statistics were used to compare proportions and means; correlation coefficients were used to describe associations. Logistic models were fit to the data to determine multivariate associations. Modification of Diet in Renal Disease (MDRD) formula was used to estimate GFR, and CKD was defined as a glomerular filtration of < 60 mL/min/1.73 m. (2) Concurrent health conditions observed included anemia, hypertension, diabetes, congestive heart failure (CHF), cerebrovascular disease, dementia, dyslipidemia, PVD, and obesity. Heart diseases for study purposes included congestive heart failure and coronary artery disease.

RESULTS

Twenty-three percent of subjects had CKD. The mean age for eGFR < 60 was 70.8 [+ or -] 13, and for eGFR > 60, it was 61.7 [+ or -] 14. Study participants were 53.9% male and 65.6% African-American. The demographic and co-morbidity profile of the study population differed considerably across age categories (Table 1). Figure 1 describes the distribution of CKD staging by resident age. Interestingly, the majority of patients were in the young group (30-65), which is unusual for nursing homes.

The predominant comorbidities found in this cross-sectional study group were hypertension (75%), gastro esophageal reflux disease (GERD) (40%), obesity (39%), dyslipidemia (35%), depression (34%), anemia (32%), diabetes (32%), cerebrovascular accident (CVA) (27%), and chronic kidney disease (CKD) (26%). In those above 75 years of age, the major comorbidities were degenerative joint disease (DJD) (80%), cancer (60%), peripheral vascular disease (PVD) (57%), COPD (50%), dementia (45%), CKD (44%), and cardiovascular disease, including congestive heart failure and coronary artery disease (38%) (Table 2).

The number of medications per study subject was correlated to eGFR. Table 3 depicts the number and percentage of patients in each category of number of medication taken across the age groups, but there was an inverse relationship between the two: A higher number of medications per subject correlated with a lower GFR.

Table 4 presents a cross-sectional review of the frequency of subjects having serum albumin < 3.0 g/dL, serum creatinine > 1.3 mg/dL, eGFR < 30 mL/min/1.73[m.sup.2], eGFR between 30-59 mL/min/1.73[m.sup.2], eGFR > 60 mL/min/1.73 [m.sup.2], Hb <11.0 g/dL, and HbA1c > 6.5%. Forty-four percent of the subjects above the age of 75 had an eGFR of < 60 mL/min/1.73[m.sup.2].

Among the co-morbidities associated with eGFR found to be statistically significant were anemia (Hb < 10) (p = 0.04), obesity (BMI > 30) (p = 0.02), cerebrovascular disease (CVD+CVA+PVD)(p=0.03), and diagnosed hypertension (p=0.04). Dyslipidemia was not found to be significantly correlated to CKD (p=0.08), nor was diabetes found to be significantly correlated (p=0.6), which could be due to the small number of diabetic subjects in the study sample (Table 5, Figure 2).

Logistic regression analysis showed that being more than 65 years old, being male, having a positive history of cardiovascular disease (including congestive heart failure and coronary artery disease), and being obese (BMI > 30) were statistically associated with low eGFR. However, when hemoglobin was added to the model, only older age and low levels of hemoglobin remained significant predictors of low levels of eGFR (Table 6). Patients older than 65 years showed a risk of CKD that was 4.2 times higher than that of their younger counterparts. Individuals with hemoglobin levels < 10 mg/dL and between 10-12 mg/ dL showed a risk of CKD that was increased 17.8 and 14.0 times, respectively, compared to those with hemoglobin > 12 mg/dL.

DISCUSSION

CKD is a public-health problem. The large numbers of non-dialysis CKD cases, the associated elevated cardiovascular risk, and the high costs of renal replacement therapy have made the identification of CKD patients and the quantification of CKD-related co-morbidities a key priority in the strategies of public-health agencies worldwide. (10-12)

The prevalence of CKD increases from 15-30% in the elderly and is more than 50% in patients with cardiovascular and metabolic diseases. (13) Epidemiologic studies have documented a dramatic age-related rise in the prevalence of CKD and anemia. Anemia can be caused by a reduction in the erythropoietin production within the kidney; however, multiple medical problems, especially in the nursing-home population, make the causal relationship more complex; male gender chronic inflammation, malnutrition, polypharmacy, GI bleeding, and impaired hepatic reserves can have effects on the hematologic system and be related to the development of anemia. These two common chronic conditions (Anemia and CKD) are associated with increases in morbidity and mortality, functional decline, hospitalizations, and increased healthcare costs. Epidemiologic data from NHANES III and the Kidney Early Evaluation Program (KEEP) of the National Kidney Foundation shows an increase in the prevalence of anemia (hemoglobin < 12.0 g/dL) in those aged 61 years and older in the presence of stage 3 CKD or higher (GFR < 60 mL/min/1.73[m.sup.2]). More than half of those older than 75 years with stage 3 or higher CKD have anemia as well. (14)

The group of patients in the present study represents the unique population of an academic-affiliated nursing home. Interestingly, the majority of patients were in the age range of 30 to 65 years, which might have affected some of the results of the study. As expected, the GFR decreased in direct correlation to the increase of the residents' age. Reasons for the high number of relatively young patients in this group may include individuals affected with early disability, developmental anomalies, and other neurodegenerative conditions that merit admission into nursing home. This might be the reason certain cardiovascular conditions such as congestive heart failure and coronary artery disease did not appear prevalent in this population. Moreover, this fact might have affected some results of this cross-sectional study.

The prevalence of CKD in this group of patients seems to be lower compared to that of other studies, in which approximately 50% of nursing home residents are affected by CKD, as defined by the parameters described herein. This discrepancy may be connected to the aforementioned relative youth of this study's population in comparison to other cohorts. Interestingly, the lower prevalence of CKD in this group of patients persisted in spite of the fact that the majority of patients are African-American. Many reports have showed that African-Americans may have a higher prevalence of CKD. (1) Finally, the burden of comorbidities must also be taken into consideration; in this study, the average number of comorbidities was lower than the number observed in others. (1)

The Renal Data System, USRDS 2012 Annual Data Report showed that between 1988-1994 and 2005-2010, the overall prevalence estimate for CKD--defined by an eGFR < 60 ml/ min/1.73 m2 or an ACR [greater than or equal to] 30 mg/g--rose from 12.3% to 14% for the general population. The largest relative increase, from 25.4% to 40.8%, was seen in those with cardiovascular disease. For eGFR < 60, prevalence rose from 4.9% to 6.7%, with the largest increase in those age 40-59; for ACR [greater than or equal to] 30 mg/g, the estimate rose from 8.8% to 9.4% (Table 7). (17) Among our relatively young population there was prevalence of CKD of 26%, 41% in those from 30-65 years of old, 15% among 66-75 years old, and 44% in those > 75 years old. It is noteworthy that in conjunction with other findings, anemia and old age (> 70) appear to be the two crucial comorbidities contributing to the aggravation of CKD, something that has been corroborated by other studies. Other variables revised in the current study--such as obesity, cardiovascular risk factors, and number of medications - showed an increased risk for the development of CKD. (1,3) The pathway by which anemia might be related to CKD is through chronic inflammation. This has been identified as one of the main mechanisms to worsening CKD. (16) In the case of obesity as risk factor, it has been found to cause albuminuria and an increased risk for CKD. (16) Obesity (BMI> 30) is a recognized risk factor for CKD. (15,16)

The relationship between obesity and CKD in the nursing home has not been evaluated in depth. In this cross-sectional study, obese patients represented close to 40% of the population, which appears to be very high compared to findings in other studies. Whether obesity is a significant contributing factor for the development of CKD in the nursing-home setting is still unknown.

Limitations of this study include its cross-sectional nature, peculiar characteristics of this population, and small number of subjects which may not allow these results to be generalized to other populations.

CONCLUSIONS

This cross-sectional study showed that our population was unique in terms of its age and reasons for nursing home admission. Factors associated with CKD in our study include age > 65 years old, being male, having a positive history of cardiovascular disease (including congestive heart failure and coronary artery disease), anemia, polypharmacy including NSAIDS, and being obese (BMI > 30). Further analysis showed that age and anemia are the strongest factors associated with CKD in our population. Management targeted at CKD risk factor reduction may play a vital role in controlling the magnitude of this disease. Prospective studies to investigate the relationship between gender, a BMI greater than 30, cardiovascular disease, and CKD and its complications are warranted.

REFERENCES

(1.) McClellan WM, Resnick B, Lei L, et al. Prevalence and severity of chronic kidney disease and anemia in the nursing home population. J Am Med Dir Assoc. 2010 Jan; 11(1):33-41.Epub 2009 Nov 6.

(2.) Epstein M. Aging and the kidney. J Am Soc Nephrol. 1996Aug; 7(8):1106-22.

(3.) Carter JL, O'Riordan SE, Eaglestone GL, et al. Chronic kidney disease prevalence in a UK residential care home population. Nephrol Dial Transplant. 2008 Apr; 23(4):1257-64. Epub 2007 Nov 19.

(4.) Coresh J, Astor BC, Greene T, et al. Prevalence of chronic kidney disease and decreased kidney function in the adult US population: Third National Health and Nutrition Examination Survey. Am J Kidney Dis. 2003; 41:1-12.

(5.) Carter JL, O'Riordan SE, Eaglestone GL, et al. Bone mineral metabolism and its relationship to kidney disease in a residential care home population: A cross-sectional study. Nephrol Dial Transplant. 2008 Nov; 23(11):3554-65. Epub 2008 Jun 10.

(6.) Stevens LA, Li S, Wang C. ,et al Prevalence of CKD and comorbid illness in elderly patients in the United States: Results from the Kidney Early Evaluation Program (KEEP). Am J Kidney Dis. 2010 Mar; 55(3 Suppl 2):S23-33.

(7.) Gorini A, Costanzo AM, Egan CG, et al. Renal status in adult volunteers in central Italy: Results from Family Abbott Renal Disease Monitoring Project (FARM) study. J Nephrol. 2011 Sep 20:0. doi: 10.5301/jn.5000027. [Epub ahead of print]

(8.) Schnelle J, Osterweil D, Globe D, et al. Chronic kidney disease, anemia, and the association between chronic kidney disease-related anemia and activities of daily living in older nursing home residents. J Am Med Dir Assoc. 2009 Feb; 10(2):120-6. Epub 2008 Dec 20.

(9.) Noble H. An aging renal population--Is dialysis always the answer? Br J Nurs. 2011 May 13-26; 20(9):545-7.

(10.) Schieppati A, Remuzzi G. Chronic renal diseases as a public health problem: Epidemiology, social, and economic implications. Kidney International. 2005; 68, S7-S10.

(11.) Bowling CB, Inker LA, Gutierrez OM, at al. Age-specific associations of reduced estimated glomerular filtration rate with oncurrent chronic kidney disease complications. Clin J Am Soc Nephrol. 2011 Dec; 6(12):2822-8. Epub 2011 Oct 27.

(12.) De Nicola L, Donfrancesco C, Minutolo R, et al Epidemiology of chronic kidney disease in Italy: Current situation and contribution of the CARHES study. G Ital Nefrol. 2011 Jul-Aug; 28(4):401-7.

(13.) El Nahas AM, Bello AK. Chronic kidney disease: The global challenge. Lancet. 2005; 365(9456): 331-40.

(14.) Robinson BE. Epidemiology of chronic kidney disease and anemia. J Am Med Dir Assoc. 2006; 7(9): S3-S6.

(15.) Burton JO, Gray LJ, Webb DR, et al. Association of anthropometric obesity measures with chronic kidney disease risk in a non-diabetic patient population. Nephrol Dial Transplant. September 29, 2011 doi: 10.1093/ndt/gfr574

(16.) Tanner RM, Brown TM, Muntner P. Epidemiology of obesity, the metabolic syndrome, and chronic kidney disease. Curr Hypertens Rep. 2012; 14(2):152-9.

(17.) U S Renal Data System, USRDS 2012 Annual Data Report: Atlas of Chronic Kidney Disease and End-Stage Renal Disease in the United States, National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 2012. (The data reported here have been supplied by the United States Renal Data System (USRDS). The interpretation and reporting of these data are the responsibility of the author(s) and in no way should be seen as an official policy or interpretation of the U.S. government)

Erwin A. Aguilar, PharmD, MSc, MPH; Hina Ashraf, MD; Maria Frontini, PhD; Marco Ruiz, MD, MPH; Thomas M. Reske, MD, PhD; Charles Cefalu, MD, MS

Dr. Aguilar is with the Section of Nephrology and Hypertension, School of Medicine at Louisiana State University Health Sciences Center in New Orleans. He is also a part of the Section of Geriatric Medicine, along with Drs. Ashraf, Ruiz, Reske, and Cefalu. Dr. Ruiz is also with the Section of Infectious Diseases and Dr. Reske is also with the Section of Hematology/Oncology. Dr. Frontini is with the School of Public Health, Department of Epidemiology, LSUHSC-New Orleans.

Table 1: Population Characteristics: Demographics (n = 102)

Demographics       Frequency                Age

                                30-65      66-75       > 75
                               (n = 59)   (n = 14)   (n = 29)

                     n (%)      n (%)      n (%)      n (%)
African-American    67 (66)    40 (60)     8 (12)    19 (28)
Caucasian           34 (33)    18 (18)     6 (18)    10 (29)
Other                1 (1)      1 (1)
Males               55 (54)    33 (60)     8 (15)    14 (25)
Females             47 (46)    26 (55)     6 (13)    15 (32)

Table 2: Population Characteristics: Comorbidities

Co-morbidities                           Frequency

                                                       30-65 (n = 59)

                                           n (%)           n (%)
Hypertension                              77 (75)         38 (49)
Gastro Esophageal Reflux Disease          41 (40)         26 (63)
  (GERD)
Obesity (Body Mass Index > 30)            40 (39)         25 (63)
Dyslipidemia                              36 (35)         23 (64)
Depression                                35 (34)         23 (66)
Anemia                                    33 (32)         14 (42)
Diabetes                                  33 (32)         18 (55)
Dementia                                  33 (32)         13 (39)
Cerebrovascular Accident (CVA)            28 (27)         15 (54)
Chronic Kidney Disease (CKD)              27 (26)         11 (41)
Cardiovascular Disease (CHF and CAD)      29 (28)         13 (44)
Cancer                                    10 (10)          2 (20)
Glaucoma                                   9 (9)           3 (33)
Chronic obstructive pulmonary disease      8 (8)           3 (38)
  (COPD)
Dysphagia                                  8 (8)           6 (75)
Hypothyroidism                             7 (7)           3 (43)
Peripheral vascular disease (PVD)          7 (7)           2 (29)
Benign Prostatic Hyperplasia (BPH)         6 (6)           4 (67)
Degenerative Joint Disease (DJD)           5 (5)             0
Multiple sclerosis (MS)                    3 (3)          3 (100)
Cirrhosis                                  2 (2)           1 (50)
Human immunodeficiency virus (HIV)         2 (2)          2 (100)
Deep vein thrombosis (DVT)                 1 (1)          1 (100)

Co-morbidities

                                        66-75 (n = 14)   > 75 (n = 29)

                                            n (%)            n (%)
Hypertension                               13 (17)          26 (34)
Gastro Esophageal Reflux Disease            5 (12)          10 (24)
  (GERD)
Obesity (Body Mass Index > 30)              7 (18)          8 (20)
Dyslipidemia                                6 (17)          7 (19)
Depression                                  5 (14)          7 (20)
Anemia                                      6 (18)          13 (39)
Diabetes                                    5 (15)          10 (30)
Dementia                                    5 (15)          15 (45)
Cerebrovascular Accident (CVA)              6 (21)          7 (25)
Chronic Kidney Disease (CKD)                4 (15)          12 (44)
Cardiovascular Disease (CHF and CAD)        6 (21)          11 (38)
Cancer                                      2 (20)          6 (60)
Glaucoma                                    2 (22)          4 (44)
Chronic obstructive pulmonary disease       1 (13)          4 (50)
  (COPD)
Dysphagia                                   1 (13)          1 (13)
Hypothyroidism                              1 (14)          3 (43)
Peripheral vascular disease (PVD)           1 (14)          4 (57)
Benign Prostatic Hyperplasia (BPH)            0             2 (33)
Degenerative Joint Disease (DJD)            1 (20)          4 (80)
Multiple sclerosis (MS)                       0                0
Cirrhosis                                   1 (50)             0
Human immunodeficiency virus (HIV)            0                0
Deep vein thrombosis (DVT)                    0                0

Table 3: Population Characteristics: Medications

Number of medications/patient        Frequency

                                                      30-65 (n = 59)

                                       n(%)               n (%)

0 - 5                                 15 (15)            9 (60)
6 - 10                                63 (62)            37 (59)
> 10                                  24 (24)            13 (54)

Number of medications/patient             Age

                                   66 - 75 (n = 14)     > 75 (n = 29)

                                         n (%)              n (%)

0 - 5                                   3 (20)             3 (20)
6 - 10                                  6 (10)             20 (32)
> 10                                    5 (21)             6 (25)

Table 4: Population Characteristics: Laboratory Data

Laboratory Data                       Frequency

                                                    30-65 (n = 59)

                                      n (%)         n (%)

GFR > 60 mL/min/1.73 (m.sup.2)        85 (83)       52 (61)
Serum Albumin (< 3.0 g/dl)            19 (19)       10 (53)
Hemoglobin < 11 g/dl                  19 (19)       7 (37)
Creatinine > 1.3 mg/dl                18 (18)       7 (39)
HbA1c > 6.5%                          11 (11)       8 (73)
GFR 30 - 59 mL/min/1.73 (m.sup.2)     9 (9)         4 (44)
GRF < 30 mL/min/1.73 (m.sup.2)        7 (7)         2 (29)

Laboratory Data

                                      66-75 (n = 14)     > 75 (n = 29)

                                      n (%)              n (%)

GFR > 60 mL/min/1.73 (m.sup.2)        11 (13)            22 (26)
Serum Albumin (< 3.0 g/dl)            3 (16)             6 (32)
Hemoglobin < 11 g/dl                  2 (11)             10 (53)
Creatinine > 1.3 mg/dl                4 (22)             7 (39)
HbA1c > 6.5%                          1 (9)              2 (18)
GFR 30 - 59 mL/min/1.73 (m.sup.2)     1 (11)             4 (44)
GRF < 30 mL/min/1.73 (m.sup.2)        2 (29)             3 (43)

Table 5: Correlation of co-morbidities to eGRF < 60 mL/
min/1.73 (m.sup.2)

Factor                      Correlation *      p

HTN                              .19          .04
Hb (< 10; 10 - 12; > 12)         .43        < .0001
                             (.19.sup.t)      .06
NSAIDS                           .01           .9
Diabetes                         .10           .6
Diabetes and Hypertension        .04           .6
CVD + CVA + PVD                  .19          .03
Obesity (BMI > 30)               .21          .02
Dyslipidemia                     .15          .08
Albumin (< 3.5)                  .02           .8

* Spearman ([dagger]) Pearson coefficients

Table 6: Significant risk factors for CKD in elderly
population

Co-morbidities   Beta Co-efficiency   Risk   P
Hemoglobin

< 10                    1.04          17.8   .002
10 - 12                 0.8           14.0   .02
> 12                     0             1
Age > 65                0.71          4.2    .01

Table 7: Prevalence (%) of CKD in the NHANES population within age,
gender, race/ethnicity, & risk factor categories

                                       All CKD

                                       1988-1994        2005-2010

20-39                                  5.1              5.7
40-59                                  8.4              9.1
60+                                    32.2             35
Male                                   10.2             12.1
Female                                 14.2             15.8
Non-Hispanic white                     12.3             14.3
Non-Hispanic Blk/Af-Am                 14.5             16
Other                                  10.5             11.9
Diabetes                               43.1             40.1
Self-reported diabetes                 42.7             41.6
Hypertension                           22.2             23.2
Self-reported hypertension             25.3             26.8
CVD                                    25.4             40.8
BMI [greater than or equal to] 30      16.6             16.8
All                                    12.3             14

                                       eGFR < 60 ml/m/1.73 (m.sup.2)

                                       1988-1994        2005-2010

20-39                                  0.1              0.2
40-59                                  1.3              2.2
60+                                    19.5             24.1
Male                                   4.1              5.6
Female                                 5.6              7.7
Non-Hispanic white                     5.5              7.9
Non-Hispanic Blk/Af-Am                 4.1              6.2
Other                                  2.2              2.6
Diabetes                               15.6             19.3
Self-reported diabetes                 16.4             20.4
Hypertension                           10.4             12.9
Self-reported hypertension             12.9             15.6
CVD                                    14.5             27.9
BMI [greater than or equal to] 30      6.2              7.4
All                                    4.9              6.7

                                       ACD [greater than or equal to]
                                         30 mg/g

                                       1988-1994        2005-2010

20-39                                  5                5.7
40-59                                  7.7              7.6
60+                                    18.3             18.4
Male                                   7.4              8.6
Female                                 10.2             10.2
Non-Hispanic white                     8.2              8.6
Non-Hispanic Blk/Af-Am                 12.7             12.6
Other                                  9.2              10.6
Diabetes                               36.3             29.9
Self-reported diabetes                 35.9             30.8
Hypertension                           15.4             14.8
Self-reported hypertension             17.1             16.7
CVD                                    16.6             24.3
BMI [greater than or equal to] 30      12.3             11.7
All                                    8.8              9.4

Reprinted from: US Renal Data System, USRDS 2012 Annual Data Report:
Atlas of Chronic Kidney Disease and Endstage Renal Disease in the United
States, National Institutes of Health, National Institute of Diabetes and
Digestive and Kidney Diseases, Bethesda, MD, 2012. (17)
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Author:Aguilar, Erwin A.; Ashraf, Hina; Frontini, Maria; Ruiz, Marco; Reske, Thomas M.; Cefalu, Charles
Publication:The Journal of the Louisiana State Medical Society
Article Type:Report
Geographic Code:1U7LA
Date:Sep 1, 2013
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