Sociodemographic factors and uncomplicated cystitis in women aged 15–50 years: a nationwide Swedish cohort registry study (1997–2018)

Background: Symptoms suggestive of uncomplicated cystitis constitutes one of the most common reasons to seek health care in otherwise healthy women. Previous studies regarding the relationship between sociodemographic factors and uncomplicated cystitis are limited, mainly because of the lack of nationwide population-based data from primary healthcare settings, where most uncomplicated cystitis are diagnosed. Methods: A Swedish nation-wide open cohort study consisting of 2 044 065 females who were 15–50 years of age during the study period (1997–2018) was conducted. The outcome was first event uncomplicated cystitis diagnosed in primary health care rather than an assessment of the ''true'' incidence, which is not feasible in nationwide datasets. Cox regression models were used in the statistical analyses. Findings: The study identified 546 076 first events of uncomplicated cystitis (26•7% of the study population), corresponding to an incidence rate per 100 person-years of 2•91 (95% CI 2•90–2•91). In fully adjusted models, rural living was associated with lower risks of uncomplicated cystitis (Hazard ratio, HR, 0•67; 95% CI, 0•66–0•68) compared to urban living, while both Middle Eastern/North African (HR, 1•15; 95% CI, 1•14–1•16) and Latin American/Caribbean (HR, 1•24; 95% CI, 1•22–1•27) women had higher risks compared to Swedish women. Low education and low income were also associated with higher risks compared to high education and high income. Interpretation: This study presents novel risk factors associated with uncomplicated cystitis in women. The findings may help health care workers in the treatment of women with symptoms of uncomplicated cystitis. Funding: The Primary Healthcare Management and ALF funding (Region Skåne, Sweden) and the Swedish Research Council.