The temporal association of hyperhidrosis and its co-morbidities - a nationwide hospital-based cohort study

BACKGROUND: Research on hyperhidrosis comorbidities has documented the co-occurrence of diseases but has not provided information about temporal disease associations.

OBJECTIVE: To investigate the temporal disease trajectories of individuals with hospital diagnosed hyperhidrosis.

METHODS: This is a hospital-based nationwide cohort study including all patients with a hospital contact in Denmark between 1994 and 2018. International Classification of Diseases version-10 diagnoses assigned to inpatients, outpatients and emergency department patients were collected from the Danish National Patient Register. The main outcome was the temporal disease associations occurring in individuals with hyperhidrosis, which was assessed by identifying morbidities significantly associated with hyperhidrosis and then examining whether there was a significant order of these diagnoses using binomial tests.

RESULTS: Overall, 7,191,519 patients were included. Of these, 8,758 (0.12%) patients had localized hyperhidrosis (5,674 female sex [64.8%]; median age at first diagnosis 26.9 [interquartile range 21.3-36.1]) and 1,102 (0.015%) generalized hyperhidrosis (606 female sex [59.9%]; median age at first diagnosis 40.9 [interquartile range 26.4-60.7]). The disease trajectories comprised pain complaints, stress, epilepsy, respiratory and psychiatric diseases. The most diagnosed morbidities for localized hyperhidrosis were abdominal pain (relative risk [RR]=121.75; 95% Confidence Interval [CI] 121.14-122.35; p<0.001), soft tissue disorders (RR=151.19; 95% CI 149.58-152.80; p<0.001) and dorsalgia (RR=160.15; 95% CI 158.92-161.38); p<0.001). The most diagnosed morbidities for generalized hyperhidrosis were dorsalgia (RR=306.59; 95% CI 302.17-311.02; p<0.001), angina pectoris (RR=411.69; 95% CI 402.23-421.16; p<0.001) and depression (RR=207.92; 95% CI 202.21-213.62; p<0.001). All these morbidities were diagnosed before hyperhidrosis.

CONCLUSIONS: This paper ascertains which hospital-diagnosed morbidities precede hospital-diagnosed hyperhidrosis. As hyperhidrosis mainly is treated in the primary health care sector, the trajectories suggests that these morbidities may lead to a worse disease course of hyperhidrosis that necessitates treatment in hospitals. Treating these morbidities may improve the disease course of hyperhidrosis.