Trends in the Incidence and Recurrence of Inpatient-Treated Spontaneous Pneumothorax, 1968-2016

IMPORTANCE Spontaneous pneumothorax is a common disease known to have an unusual epidemiological profile, but there are limited contemporary population-based data. OBJECTIVE To estimate the incidence of hospital admissions for spontaneous pneumothorax, its recurrence and trends over time using large, longstanding hospitalization data sets in England. DESIGN, SETTING, AND PARTICIPANTS A population-based epidemiological study was conducted using an English national data set and an English regional data set, each spanning 1968 to 2016, and including 170 929 hospital admission records of patients 15 years and older. Final date of the study period was December 31, 2016. EXPOSURES Calendar year (for incidence) and readmission to hospital for spontaneous pneumothorax (for recurrence). MAIN OUTCOMES AND MEASURES Primary outcomes were rates of hospital admissions for spontaneous pneumothorax and recurrence, defined as a subsequent hospital readmission with spontaneous pneumothorax. Record-linkage was used to identify multiple admissions per person and comorbidity. Risk factors for recurrence over 5 years of follow-up were assessed using cumulative time-to-failure analysis and Cox proportional hazards regression. RESULTS From 1968 to 2016, there were 170 929 hospital admissions for spontaneous pneumothorax (median age, 44 years [IQR, 26-88]; 73.0% male). In 2016, there were 14.1 spontaneous pneumothorax admissions per 100 000 population 15 years and older (95% CI, 13.7-14.4), a significant increase compared with earlier years, up from 9.1 (95% CI, 8.1-10.1) in 1968. The population-based rate per 100 000 population 15 years and older was higher for males (20.8 [95% CI, 20.2-21.4]) than for females (7.6 [95% CI, 7.2-7.9]). Of patients with spontaneous pneumothorax, 60.8%(95% CI, 59.5%-62.0%) had chronic lung disease. Record-linkage analysis demonstrated that the overall increase in admissions over time could be due in part to an increase in repeat admissions, but there were also significant increases in the annual rate of first-known spontaneous pneumothorax admissions in some population subgroups, for example in women 65 years and older (annual percentage change from 1968 to 2016, 4.08 [95% CI, 3.33-4.82], P < .001). The probability of recurrence within 5 years was similar by sex (25.5%[95% CI, 25.1%-25.9%] for males vs 26.0% [95% CI, 25.3%-26.7%] for females), but there was variation by age group and presence of chronic lung disease. For example, the probability of readmission within 5 years among males aged 15 to 34 years with chronic lung disease was 39.2%(95% CI, 37.7%-40.7%) compared with 19.6%(95% CI, 18.2%-21.1%) in men 65 years and older without chronic lung disease. CONCLUSIONS AND RELEVANCE This study provides contemporary information regarding the trends in incidence and recurrence of inpatient-treated spontaneous pneumothorax.