High adherence to nocturnal-only frequency volume charts in diagnosing nocturia: A Pilot Study

Quantitative assessment of urine output by means of a frequency volume chart (FVC) is a standard of care for the workup of nocturia but limited by suboptimal return rates and incomplete data entry. Nocturia, defined by the International Continence Society (ICS) as the need to wake at night to void, often necessitates comprehensive evaluation. While FVCs are typically maintained across the entire 24 h period, restricting urine collection to only the hours of intended sleep have been proposed as a patient-centered approach for increasing return rates. This study aimed to determine return rates for nocturnal-only FVCs and identify demographic or clinical factors affecting chart completion. Three prospective studies were conducted between 2021 and 2024 at a Brooklyn academic medical center. Study 1 investigated the relationship between nocturia and blood pressure (BP) elevation in adolescents. Study 2 evaluated fluid overload and its association with nocturia prevalence in adults. Study 3 investigated the relationship between nocturia and BP in adults. In each study, participants were provided containers and FVC sheets for nocturnal voiding documentation. Follow-up occurred via cellphone. Data included demographics, self-reported voids, and completed FVC information. Among 349 patients, aged 10-103 years, the cumulative FVC return rate was 90.5% (95% CI 87.0%–93.4%). Age, gender, and race were similar among returners and non-returners. Non-returners, however, self-reported more voids, which may indicate differing behavioral or clinical characteristics. Among 316 patients who returned FVCs, 314 (99.4%) completed every required chart category (95% CI 97.7%–99.9%). Among three studies employing the use of nocturnal-only FVC return, there were high rates of FVC return and accurate completion. Although direct comparative data with 24 h FVCs were not assessed, the high adherence rates suggest nocturnal-only FVCs offer a patient-centered and effective alternative or complement for nocturia evaluation. Future studies comparing utility and return rates between nocturnal-only and 24 h FVCs may further elucidate their comparative effectiveness.