Disparities in the Prevalence of Urinary Diseases Among Prisoners in Taiwan: Population-Based Cross-Sectional Study

Background: Prisoner health is a major global concern, with prisoners often facing limited access to health care and enduring chronic diseases, infectious diseases, and poor mental health due to unsafe prison environments, unhygienic living conditions, and inadequate medical resources. In Taiwan, prison health is increasingly an issue, particularly concerning urinary diseases such as urinary tract infections. Limited access to health care and unsanitary conditions exacerbate these problems. Urinary disease epidemiology varies by sex and age, yet studies in Asia are scarce, and comprehensive data on urinary diseases in Taiwanese prisons remain limited.

Objective: This study aimed to investigate the prevalence of urinary diseases among Taiwanese prisoners and explore the differences in disease prevalence between men and women, as well as across different age groups.

Methods: This study used data on prisoners from the National Health Insurance Research Database covering the period from January 1 to December 31, 2013. Prisoners covered by National Health Insurance who were diagnosed with urinary diseases, identified by ICD-9-CM (International Classification of Diseases, Ninth Revision, Clinical Modification) codes 580-599 based on their medical records, and had more than one medical visit to ambulatory care or inpatient services were included. Sex- and age-stratified analyses were conducted to determine the differences in the prevalence of urinary diseases.

Results: We examined 83,048 prisoners, including 2998 with urinary diseases. The overall prevalence of urinary system diseases among prisoners was 3.61% (n=2998; n=574, 6.64% in men and n=2424, 3.26% in women). The prevalence rate in men was significantly lower than that in women (prevalence ratio: 0.46, P<.001). In age-stratified analysis, the prevalence rate among prisoners aged >40 years was 4.5% (n=1815), compared to 2.77% (n=1183) in prisoners aged ≤40 years. Prisoners aged >40 years had a higher prevalence (prevalence ratio: 1.69, P<.001). Other disorders of the urethra and urinary tract (ICD-9-CM: 599), including urinary tract infection, urinary obstruction, and hematuria, were the most prevalent diseases of the urethra and urinary tract across age and sex groups. Women and older prisoners had a higher prevalence of most urinary tract diseases. There were no significant sex-specific differences in adjusted prevalence ratios for acute glomerulonephritis, nephrotic syndrome, kidney infections, urethritis (nonsexually transmitted), or urethral syndrome. However, based on the age-specific adjusted prevalence ratio analysis, cystitis was more prevalent among younger prisoners (prevalence ratio: 0.69, P=.004).

Conclusions: Urinary system infections and inflammation are common in prisons. Our findings advocate for policy reforms aimed at improving health care accessibility in prisons, with a particular focus on the needs of high-risk groups such as women and older prisoners. Further research linking claims data with prisoner information is crucial to providing more comprehensive medical services and achieving health equity.