Prevalence of night sweats in primary care patients: an OKPRN and TAFP-Net collaborative study - Original Research - Statistical Data Included

Journal of Family Practice, May, 2002 by James W. Mold, Migi K. Mathew, Shuaib Belgore, Mark DeHaven

In retrospect, the omission of the variable "panic attacks" from the Oklahoma cards was a mistake, since this variable was correlated with pure night sweats in women. It may have been more strongly associated with pure night sweats in men as well, if the number of respondents to this question had been larger. Also, some men complained of hot flashes, and when they did, they were more likely to have night sweats and panic attacks, suggesting that both hot flashes and night sweats in men should prompt physicians to ask additional questions about panic disorder. Although race was also omitted from the Oklahoma cards, this variable did not seem to be associated with differences in night sweats prevalence or association among those for whom this information was available.

The definition and description of night sweats used in this study were arbitrary and may have influenced the prevalence rates obtained. We attempted to exclude environmental temperature as a cause. Although the definitions provided clearly stated "within the last month," the data collection cards did not specify a time interval. This may have resulted in some variation in interpretation.

The decisions that were made regarding logistic modeling strategies were conservative and may have excluded some important variables. However, with so many variables and no basis on which to judge a priori, we felt that a conservative approach was best. The decision to include in the models variables (eg, sleep problems and sedatives that might be considered consequences) rather than causes of night sweats, was also arbitrary and may have affected the results. An alternative explanation of the associations found between night sweats and sleep problems is that those who are unable to sleep for other reasons are more likely to notice excessive sweating than those who are asleep.

Future studies should more carefully examine factors found in this study to be associated with night sweats, such as panic attacks and sleep disorders, and other potential etiologic factors not considered, such as tobacco abuse, allergic diseases, migraines, congestive heart failure, and chronic lung disease. Given the high prevalence, future studies examining etiology should include appropriate control groups. Case-control and prospective studies should evaluate the natural history of both night sweats patterns and their association with quality and length of life. The potential value of night sweats as a clue to the early diagnosis of important under-recognized pathologies, such as sleep disorders and panic attacks, should be investigated, Finally, randomized trials of treatments to reduce the frequency, severity, and impact of night sweats should be undertaken once the potential causes have been better elucidated.

TABLE 1

Percentage of patients with pure night sweats
and night and day sweats

Patient group,     Pure night    Night and day    Any night
by sex and age,      sweats         sweats          sweats
in years           % (95% CI)     % (95% CI)      % (95% CI)

All patients       23 (21-24)      18 (16-20)     41 (39-43)
Men                22 (19-26)      12 (9-14)      34 (30-38)
  18-40            20 (14-26)      14 (9-19)      35 (28-42)
  41-55            25 (18-32)      14 (9-19)      40 (33-47)
  56-69            24 (16-32)      12 (6-18)      38 (30-46)
  70               20 (13-27)       6 (2-10)      26 (19-33)
Women              23 (21-25)      21 (19-24)     44 (42-47)
  18-40            22 (18-26)      19 (15-23)     42 (38-46)
  41-55            29 (24-34)      32 (28-37)     61 (56-66)
  56-69            22 (18-27)      23 (18-28)     43 (37-49)
  70               19 (14-24)       9 (5-13)      29 (24-34)

CI denotes confidence interval.
TABLE 2

Associations between independent variables and night
sweats in men and women after using logistic regression
modeling to control for all other variables

Patient
group             Pure night sweats

          Variable                OR (95% CI)

All       Panic attacks           4.80 (1.69-13.63)

Men       Sleep                   2.54 (1.7-3.8)
          problems

Women     Hot flashes             3.35 (1.13-9.95)
          Panic attacks           4.47 (1.20-16.69)

Patient
group             Night and day sweats

          Variable                OR (95% CI)

All       Age *                   0.99 per yr (0.98-0.99)
          BMI                     1.03 per unit (1.02-1.05)
          Hot flashes             7.23 (5.45-9.58)
          Chronic infections      2.05 (1.22-3.42)
          Sleep problems          1.54 (1.16-2.04)
          SSRIs                   1.82 (1.22-2.70)
          TCAs                    2.43 (1.25-4.74)
          Other antidepressants   2.85 (1.66-4.89)
          Xanthines               5.48 (1.60-18.81)

Men       Weight                  per lb (1.00-1.02)
          Hot flashes             9.41 (4.50-19.8)
          Alcohol                 3.87 (1.60-9.20)

Women     Weight                  1.01 per lb (1.00-1.01)
          Sleep problems          1.74 (1.30-240)
          Hot flashes             6.75 (5.00-9.20)
          SSRIs                   2.01 (1.30-3.10)
          Other antidepressants   2.85 (1.70-5.90)
          Antihistamines          1.88 (1.20-2.90)

* Younger age was associated with a greater likelihood of night
and day sweats. Otherwise, presence of or increasing amount of each
variable was associated with a greater likelihood of night sweats.

OR denotes odds ratio; CI, confidence interval; BMI, body mass
index; SSRIs, selective serotonin reuptake inhibitors; TCAs,
tricyclic antidepressants.