The incidence of adhesive capsulitis and COVID-19 pandemic effect.

Background: There are multiple pieces of evidence in the literature that coronavirus disease 2019 (COVID-19) has a pronounced effect on physiological health. There is little existing literature that has studied the pandemic's impact on adhesive capsulitis (AC) incidence. This study aimed to compare the incidence of primary AC before and during the pandemic.

Methods: A retrospective cohort study was done to establish the incidence of primary AC during the COVID-19 pandemic, from March 2020 to March 2021, the pandemic period, and from March 2019 to March 2020, the control period. During these periods, all patients diagnosed with primary AC were included. Patients were also categorized into three different treatment groups according to corticosteroid injection status (none, 1 injection, and 2 injections). The waiting time for the appointment was calculated as a possible confounding factor. Statistical analysis used the chi-square for categorical variables and the Student test for continuous variables.

Results: There were 69 patients diagnosed with primary AC out of 704 new referrals during the pandemic. One year earlier, a total of 73 patients were diagnosed with primary AC out of 1148 new referrals. Representing a relative increase of 3.5% ( = .086) in the incidence of primary AC. No significant differences were found between the control and the pandemic groups in regard to the distribution of patients per treatment group ( = .13), age ( = .49), sex ( = .21), laterality ( = .54), diabetic disease ( = .45), and thyroid disease ( = .62).

Conclusion: There was a nonstatistically significant increase in the incidence of primary AC during the COVID-19 pandemic. No other significant differences were found. Further research is still needed to evaluate the relationship between the COVID-19 pandemic and AC.