This study is a randomized, double-blind, controlled trial, parallel group study.
After approval by the Ethics Committee and a pretest, the study was conducted from December 2021 to March 2022 and followed the Consolidated Standards of Reporting Trials (CONSORT) reporting guideline.
Study participants were people aged 40-79 years who have nocturia and who were recruited from among the 300,000 members of a Japanese own web-based travel agency with a large proportion of senior citizen members.
Participants were stratified and randomized by age, gender, and pre-existing disease using a random number table by the web-based company. Using the double-blind method, participants were divided into two groups: the intervention group wore commercially available compression knee-high socks and the control group wore regular knee-high socks made of the same material as the intervention group (both made in Japan).
The compression knee-high socks worn by the intervention group were made of 32.7% cotton, 20.7% rayon, 20.7% nylon, 20.7% polyurethane, 4% ester, and 1.2% other materials, with compression values of 23.8 hPa at the sole, 17.2 hPa at the ankle, and 10.4 hPa at the calf.
The regular knee-high socks worn by the control group were made of 34.7% cotton, 27.2% rayon, 24.5% ester, 7.7% polyurethane, and 5.9% other materials, with compression values of 6.9 hPa at the sole, 5.0 hPa at the ankle, and 4.6 hPa at the calf.
The study was conducted for a total of 21 days, including a 7-day pre-observation period, the 3 days from day 5 to 7, during which the participants became accustomed to the study, were used as the baseline. Participants wore each pair of knee-high socks (washed daily) for at least 8 hours per day from morning to evening. The survey consisted of participants answering five questions, including the number of times they urinated at night, every day for 21 days. They also responded to the Japanese version of N-QOL at the baseline after 14 days of wearing the knee-high socks. Participants were given a double-blind telephone survey by the web company if they were unable to respond online. After the survey, all the knee-high socks were collected, and their condition of use and the presence of defects were verified by an expert.
Statistical sample sizes were calculated. The number of participants allowed adequate assessment of the effects of wearing knee-high socks. All study data was listed, summarized and plotted.
After confirming the normality of the percent change from baseline for the intervention and control groups, a t-test with a two-group correspondence was used. A welch t-test was used for the difference between the two groups in the frequency of nocturnal urination and the total points of the Japanese version of N-QOL. SPSS version 28 was used. (Statistical power 80 %, P < .05)