Mechanisms and Associated Factors of Nocturia in Women Attending Two Urogynecology Clinics: A Cross-Sectional Study

Introduction: Nocturia has a multifactorial etiology, and its diagnostic approach involves, in addition to medical history and physical examination, the use of a bladder diary to define the pathophysiological mechanisms present in each case. Methods: This study investigated the prevalence of nocturia, its mechanisms, and associated factors in women with lower urinary tract symptoms attending two urogynecology clinics in the state of Rio de Janeiro, Brazil. Anamnesis, physical examination, and a 24-hour bladder diary were conducted. Two definitions of nocturia were considered: one or more nighttime voids and two or more nighttime voids. Mann-Whitney and Chi-square tests were used, with p-value ≤ 0.05 considered significant. Results: A total of 133 participants were included. The majority were aged 60 years or older (61.4%) and had three or more comorbidities (66.7%), with systemic arterial hypertension being the most prevalent (59.1%). Of the total participants, 54 (41.4%) completed the bladder diary. Among those with one or more nighttime voids (70.7%), the prevalence of nocturnal polyuria was 69.1%, reduced nocturnal bladder capacity was 17.3%, and global polyuria was 12.9%. Among participants with two or more nighttime voids (56.4%), the prevalences were respectively 68.2%, 19.1%, and 13.6%. Among the mechanisms, associations were found only with global polyuria, namely: use of insulin, body mass index and tobacco consumption. An association was also found between recurrent urinary tract infection and global polyuria in participants with two or more nighttime voids. Conclusions: The prevalence of nocturia was higher than that reported in general population studies and specialized services for lower urinary tract symptoms. Nocturnal polyuria was the most prevalent mechanism. Associations were observed between the use of insulin, body mass index, tobacco consumption, and recurrent urinary tract infection with global polyuria. No associations were found between any clinical or demographic variables and nocturnal polyuria or reduced nocturnal bladder capacity.