Our interviewers approached 7,430 individuals and 3,114 of them accepted the survey (rejection rate of 58.1 %). After 352 individuals suspended the interview, 2,695 subjects completed the survey (cooperation rate, 36.2 %; Fig. 1). The distributions of age, gender, size of residential area, and educational level were not significantly different from those of the general population of Korea (Fig. 1 and Table 1).
Fig. 1 Flow chart depicting the participation of subjects in the Korean Headache-Sleep Study. RLS: restless legs syndrome
Table 1 Sociodemographic distribution of all survey participants, the total Korean population, and of cases identified as migraine and restless legs syndrome
Sample number Total population p-value Migraine Restless legs syndrome
N (%) N (%) N (% , 95 % CI) N (% , 95 % CI)
Gender
Men 1345 (49.3a) 16,357,919 (50.6) 0.42b 36 2.7, 1.8–3.5 56 4.1, 3.0–5.1
Women 1350 (50.7a) 15,998,828 (49.4) 107 7.9, 6.5–9.4 86 6.4, 5.1–7.7
Age
19–29 542 (20.5a) 7,179,648 (22.2) 0.76b 25 4.5, 2.8–6.2 12 2.2, 1.0–3.4
30–39 604 (21.9a) 7,767,141 (24.0) 42 7.0, 5.0–9.1 34 5.6, 3.7–7.4
40–49 611 (23.1a) 8,012,377 (24.8) 39 6.5, 4.5–8.4 20 3.3, 1.9–4.7
50–59 529 (18.9a) 5,737,344 (17.7) 22 4.1, 2.4–5.9 35 6.5, 4.4–8.7
60–69 409 (15.6a) 3,660,237 (11.3) 15 3.9, 2.0–5.7 41 10.2, 7.3–13.1
Size of residential area
Large city 1,248 (46.3a) 1,5606,652 (48.2) 0.92b 76 6.1, 4.8–7.5 66 5.3, 4.1–6.5
Medium-to-small city 1,186 (44.0a) 1,4106,687 (43.6) 48 4.0, 2.9–5.1 58 4.9, 3.7–6.1
Rural area 261 (9.7a) 264,307 (8.2) 19 7.4, 4.2–10.6 18 6.8, 3.7–9.8
Educational level
Middle school or less 393 (14.9a) 6,147,782 (19.0) 0.75b 22 5.5, 3.3–7.7 41 10.5, 7.5–13.5
High school 1,208 (44.5a) 14,172,255 (43.8) 60 5.0, 3.8–6.3 62 5.1, 3.8–6.3
College or more 1,068 (39.6a) 1,2036,710 (37.2) 60 5.6, 4.3–7.0 38 3.6, 2.5–4.7
Total 2,695 (100.0a) 32,356,747 (100.0) 143 5.3, 4.5–6.2 142 5.3, 4.4–6.1
CI confidence interval
aAdjusted after age, gender, size of residential area and educational level
bCompared gender, age group, size of residential area, and educational level distributions between the sample of the present study and total population of Korea