Hypothesis / aims of study
Both frailty and nocturnal polyuria are common in the elderly and reduce their quality of life. However, there are few reports examining which factors of frailty are associated with nocturnal polyuria. The cause of nocturnal polyuria is not clear, and prevention of nocturnal polyuria is difficult. On the other hand, some of causes of frailty are clear and can be prevented. Identification of factors associated with frailty and nocturnal polyuria may lead to prevention of nocturnal polyuria. The aim of study was to investigated which factors of frailty are associated with nocturnal polyuria.
Study design, materials and methods
Patients who visited our hospital's internal medicine department between November 2022 and December 2023 and were suspected of having pre-frailty or frailty were targeted. Gender, height, weight, BMI, grip strength, walking speed, lower limb muscle strength, and complications were evaluated. To evaluate frailty, the Kihon checklist (KCL), a questionnaire for a comprehensive frailty assessment, and the modified Japanese Cardiovascular Health Study score (J-CHS) were used. To evaluate nocturnal polyuria, nocturnal polyuria index (NPi) from frequency volume chart was used. Cases with declining physical function and requiring nursing care were excluded.
Results
There were 59 patients, 28 males and 31 females. Median age was 75 years (65-93), height was 158.8 cm (142.5-178), weight was 61.8 kg (40.5-88.6), BMI was 23.8 kg/m2 (18.6-31.6), and grip strength was 24.3 kg (12.3-45.4), the 5-time standing test was 9.4 seconds (5.8-18.7), the average walking speed was 1.28 m/s (0.71-1.71). The KCL total score was 4 points (0-15), and the J-CHS total score was 1 point (0-4). NPi was 35% (11-74). Among these factors, KCL6, which is a basic ADL factor (Are you climbing stairs without using handrails or walls?), and KCL16, which is the factor that expresses motivation and physical function (Are you going out at least once a week?) was significantly associated with NPi (p = 0.031 and 0.035, respectively). Furthermore, in the frail group (KCL total score 8 or higher), there was a significant relationship between KCL total score and NPi (p = 0.037). In the non-frail group (KCL total score less than 7 points), KCL1 (Do you go out alone on the bus or train?), KCL6, and KCL16 were significantly associated with NPi (p = 0.014, 0.016, and 0.005, respectively).
Interpretation of results
Nocturnal polyuria was thought to be less common among patients who were able to take care of themselves, were willing to go out, and had sufficient physical function to go out. The results suggest that regular physical activity for maintenance of mobility and going outside regularly may be effective in preventing nocturnal polyuria.