The purpose of this study was to investigate the prevalence and risk of adhesive capsulitis
among hyperthyroidism patients. The data were obtained from the Longitudinal Health
Insurance Database 2005 (LHID 2005) in Taiwan, using 1 million participants and a
prospective population-based 7-year cohort study of survival analysis. The ambulatory-care
claim records of patients diagnosed according to the International Classification of
Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes relating to hyperthyroidism
between January 1, 2004 and December 31, 2007, were obtained. The prevalence and the
adjusted hazard ratio (HR) of adhesive capsulitis among hyperthyroid patients and the
control group were estimated. Of 4472 hyperthyroid patients, 162 (671/100 000 person-years)
experienced adhesive capsulitis during the 24 122 person-year follow-up period. The crude HR
of stroke was 1.26 (95% confidence interval [CI], 1.06 to 1.49), which was larger than that
of the control group. The adjusted HR of developing adhesive capsulitis was 1.22 (95% CI,
1.03 to 1.45) for hyperthyroid patients during the 7-year follow-up period, which achieved
statistical significance. The results of our large-scale longitudinal population-based study
indicated that hyperthyroidism is an independent risk factor of developing adhesive
capsulitis.