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A general population survey of rest cramps.

Summary

Two hundred and eighteen subjects, out of 250 individuals taken from a general practice register, returned completed questionnaires giving details about rest cramps, and a further 15 were contacted by telephone. The overall prevalence of rest cramps in the survey population was 37%. The symptom was more prevalent in older subjects. Rest cramps were most commonly experienced in the muscles of the leg, in 83% of the 86 cramp sufferers. Symptoms were usually present at night (73%). On average cramp episodes lasted for 9 min (95% CI 6.7-11.2). Most cramps sufferers experienced symptoms infrequently, but 40% had cramp episodes more than three times per week and 6% complained of at least one episode per day or night. Twenty-one per cent of cramp sufferers described their symptoms as very distressing. A minority, 32% of the 86 cramp sufferers, had reported the symptoms to a general practitioner although the 86 subjects self-rated their health more negatively than the individuals without muscle cramps. There was a significant, positive association between rest cramps and symptoms of angina or intermittent claudication although these two factors only accounted for 12% of the variance, suggesting that peripheral vascular disease may play a relevant but limited role in the aetiology of rest cramps.

Introduction

Rest cramp is a distressing condition characterized by painful, involuntary muscular contractions most commonly affecting the leg. Little is known about its cause, prevalence or treatment. It has been suggested that vascular insufficiency of the affected muscles may play a part in the aetiology [1] but there is little evidence to support this. This paper reports the first general population survey of rest cramps in the United Kingdom seeking to assess its prevalence, severity and to explore the possible association between the condition and symptoms of vascular disease.

Methods and Subjects

A postal questionnaire, which had previously been piloted on a group of outpatients, was sent to subjects selected from a general-practice register. The questionnaire enquired about the presence of cramps, their onset, frequency, timing and severity. The questionnaire was explicit in defining cramps as a painful involuntary muscle contraction which was not associated with exercise and came on at rest. Questions were also asked about whether the symptoms had been reported to a general practitioner (GP), aspects of general health, smoking habits and current medication. Specific questions relating to the presence of angina and leg claudication were also included.

The general practice had a list size of 9127 patients and comprised a mixed rural and urban population. The practice age-register was first stratified by bands and 60 subjects were randomly chosen from the 6th, 7th and 8th decade groups and 65 from the 9th and 10th decades combined making a total of 250. Data were analysed using the Number Cruncher Statistical Systems program (NCSS Kaysville, Utah 84037 USA). There were 218 (89%) questionnaire replies and fifteen of the remaining 27 subjects were interviewed by telephone.

Results

Prevalence: There were 121 female questionnaire respondents whose average age was 73 years (95% CI 71.1-74.9), slightly older than the 97 male respondents whose average age was 66 years (95% CI 64.3-68.6). Eighty-six (37%) of the respondents had had rest cramps during the preceding 2 months (Table I). There was no significant difference in cramp prevalence between men and women. The prevalence of cramps was substantially higher in older than in younger age groups (Table 1).

Table I. Prevelance of muscle cramps by age group, described
as a minor nuisance (1), a major nuisance (2) or very
distressing (3)

Age      No. with    Prevalence
group    Cramps      (%)          1 (%)     2 (%)    3 (%)

50-59     13         27           10 (77)   -        3 (13)
60-69     24         40           14 (58)   8 (34)   2 (8)
70-79     16         32            8 (50)   2 (12)   6 (38)
80-       33         54           14 (43)   9 (27)  10 (30)
Total     86         37           46 (53)  19 (53)  21 (24)


Symptoms: Of the 86 subjects who reported suffering from rest cramps, most experienced the symptoms in their leg, foot or thigh muscles (Table II), with only a minority complaining of rest cramps in muscles of the upper limb or elsewhere. Most subjects reported symptoms occurring only, or mostly, at night (73%) with 20% reporting rest cramps day and night and only a minority (7%) complaining of them mostly, or only, during the day. The mean duration of the cramp episodes was 9 min (95% CI 6.7-11.2). On average, symptoms experienced in the thigh muscle lasted longer, although not significantly so, when compared with those from muscles of the foot or leg (Table II). Overall the majority of sufferers experienced symptoms less than once per week although 40% experienced rest cramps more than three times per week and 6% suffered more than one episode every day or night.

Table II. Mean duration of cramp events occuring in feet, legs
and thighs

                  Time (min)          95% CI

Feet               8.4                5.81-11.06
Legs               9.6                7.02-12.28
Thighs            11.68               7.41-15.95

  The 95% CIs (confidence intervals) of the difference between
the mean duration of cramps in feet and legs, feet and thighs
and legs and thighs, respectively, were calculated using
unpaired, single-tailed t tests: -6.2 to 0.35, -3.9 to 2.9 and
-6.76 to 2.7.


Forty-six (53%) cramp sufferers reported their symptoms as a 'minor nuisance', 19 (22%) as a major nuisance' and 21 (24%) as 'very distressing'. There was a significant increase in the mean age of subjects self-rating their cramps to be very distressing rather than a minor nuisance (Table III).

Table III. Mean age of subjects with cramps who considered
the symptom a minor nuisance, a major nuisance or very
distressing

                           Mean age
                           (years)         95% CI

1. Minor nuisance           69.3           65.7-72.9
2. Major nuisance           72.3           67.7-77
3. Very distressing         78.5           75.2-81.7

95% CIs of differences between mean ages of the groups 1 vs.
2, 1 vs. 3 and 2 vs. 3, respectively, using unpaired, single-tailed
t tests were: -9.0 to 3.0, -15.1 to -3.0 and -11.98 to
-0.37.


The mean age at onset of symptoms within the subject group was 60 years (95% CI 57-63) with no significant difference between male and female. Symptom reporting: Of the 86 subjects with rest cramps, only 32 (37%) had reported the symptom to a GP. The mean duration of cramp episodes in these 32 (13.9min, 95% CI 8.8-19.0) was significantly longer than in the subjects not reporting the symptom to a GP (6.09 min, 95% CI 4.5-7.6). The 95% CI of the difference of the means, using an unpaired single-tailed t test, was -12.13 to -3.49. Subjects complaining of the symptom to a GP had, on average, more frequent cramps: 3 per week (95% CI 2.4-3.7) compared with 1.83 (95% CI 1.47-2.19). The 95% CI of this difference was -1.9 to -0.58. However, 40% of people having more than two episodes per week, and 45% of people whose cramps lasted more than 5 min, had not reported this to a doctor and 31% of subjects with cramps who had not reported their symptoms described them as very distressing or a major nuisance.

Subjects with rest cramps had self-reported their perceived general health and their health in relation to their peers, using a five-point ordinal scale, as more negative than those without the symptom ([X.sup.2] = 16.9, p = 0.002 and [X.sup.2] = 15.2, p = 0.0043).

Association: A linear discriminant analysis showed that a history of leg claudication (p = 0.001) and angina (p < 0.001) had a significant association with rest cramps (Wilks' lambda statistic = 0.88).

Discussion

Rest cramps receive little attention in standard medical texts despite being common. The overall prevalence in this study was 37% and was 54% in people aged 80 or more. A previous study from USA [2] has reported similar findings with 56% of veterans attending an outpatient clinic reporting symptoms. However, our study is the first survey of a community rather than a self-selected sample of hospital attenders. Its validity is further strengthened by the choice of general practice, involving both urban and rural areas, and the high overall response rate (95%).

This study confirms the widely held view that the symptoms of rest cramps predominantly afflict the muscles of the lower limb and are much commoner during the night than the day. Peripheral vascular disease may have an aetiological role in rest cramps [1]. This may explain the therapeutic value of agents such as naftidrofuryl [3]. We found that there was, a significant association between symptoms of vascular disease and rest cramps using a linear discriminant analysis model, although together these two factors were only able to account for approximately 12% of the variance. Symptoms are a poor marker for the presence of vascular disease and further studies are needed to examine the relationship between impaired peripheral circulation and rest cramps in more detail. However, as vascular disease is commoner in the lower limb than in the upper limb vessels, the preponderance of rest cramps affecting the muscles of the lower limbs, particularly the distal muscles, may be a further indication that vascular factors are important in the aetiology of the condition.

Over a third of subjects whose-cramps were frequent, lasting longer than 5 minutes and described as very distressing or a major nuisance had not reported this to a doctor. Also, subjects experiencing rest cramps perceived them as a health burden, as suggested by their more negative self-rating of health. Despite this, a significant number had not reported the symptom to their doctor. We suggest that specific questioning about muscle cramps, particularly in older people, should be undertaken to identify this relatively common condition better.

Acknowledgements

We wish to thank Dr M. Purvis and colleagues for allowing us to contact their patients for this study and Drs A. Stanners, A. Travers and C. Teale for helpful discussions.

References

[1.] Young JB, Javid M, George J. Rest cramps in the elderly. J R Coll Physician Lond 1989;20:103-6. [2.] Oboler SK, Prochazka AV, Meyer TJ. Leg symptoms in outpatient veterans. West J Med 1991;155:256-9. [3.] Young JB, Connolly MJ. Naftidrofuryl for rest cramp. Postgrad Med J 1993;69:624-6.
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Author:Naylor, J.R.; Young, J.B.
Publication:Age and Ageing
Date:Sep 1, 1994
Words:1723
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