532 Table 5. Clinical findings of chronic fatigue subgroups accord- ing to major problems associated with chronic fatigue Physical Psychological ICF CF (n=48) CF (n=64) (n=17) CFS (n=10) p-value Age (yr) 0.152 18-29 10 (20.8%) 12 (18.7%) 1 (5.9%) 2 (20.0%) 30-39 12 (25.0%) 22 (34.4%) 10 (58.8%) 2 (20.0%) 40-49 6 (12.5%) 14 (21.9%) 4 (23.5%) 2 (20.0%) 50-59 5 (10.4%) 8 (12.5%) 1 (5.9%) 4 (40.0%) ≥60 15 (31.3%) 8 (12.5%) 1 (5.9%) 0 (0.0%) Female 33 (68.7%) 46 (71.8%) 7 (41.2%) 8 (80.0%) 0.221 Education 0.038 elementary 22 (46.8%) 11 (17.2%) 0 (0.0%) 2 (20.0%) middle 13 (27.1%) 34 (53.1%) 11 (64.7%) 5 (50.0%) school university 3 (27.1%) 19 (29.7%) 6 (35.3%) 3 (30.0%) Occupation 0.267 unskilled/ 32 (66.7%) 31 (48.4%) 8 (47.1%) 5 (50.0%) semiskilled skilled 10 (20.8%) 28 (43.8%) 8 (47.1%) 5 (50.0%) professional 6 (12.5%) 5 (7.8%) 1 ( 5.8%) 0 (0.0%) Marital status 0.111 unmarried 4 (8.3%) 7 (10.9%) 1 (5.8%) 1 (10.0%) married 31 (64.6%) 46 (71.9%) 15 (88.4%) 9 (90.0%) divorced 1 (2.1%) 8 (12.5%) 1 (5.8%) 0 (0.0%) others 12 (25.0%) 3 (4.7%) 0 (0.0%) 0 (0.0%) Alcohol intake* 23 (47.9%) 18 (28.1%) 6 (35.3%) 1 (10.0%) 0.018 Current smoker 10 (21.3%) 15 (23.4%) 3 (17.6%) 1 (10.0%) 0.485 BEPSI-K 2.2±0.4 2.8±0.9 2.2±0.5 2.1±0.3 0.002 (mean±S.D.) Depression 27 (57.4%) 62 (96.9%) 11 (54.7%) 8 (80%) 0.001 (Positive rate of SDS test) CF, Chronic fatigue; CFS, Chronic fatigue syndrome; ICF, Idiopathic chronic fatigue; SDS, Zung’s self-rating depression scale; S.D., Standard deviation. *≥once per week, p<0.01 when compared to chronic fatigue associat- ed physical, chronic fatigue syndrome and idiopathic chronic fatigue sub- jects, p<0.01 when compared to chronic fatigue associated physical and idiopathic chronic fatigue subjects. C.H. Kim, H.C. Shin, C.W. Won CFS as well as in impaired short-term memory or concentra- tion, unrefreshing sleep, multi-joint pain without arthritis, and post-exertional malaise lasting more than 24 hr. In addi- tion, the tenderness of cervical and axillary lymph nodes and muscle pain showed higher frequencies in the CFS than in that of explained CF (physical and psychological CF) (Table 6). DISCUSSION This is the first study that investigated the point prevalence of CF and CFS in patients who visited community-based pri- mary care centers in Korea. There have been many epidemio- logical researches on CF and CFS in Western countries since the 1990s, but such studies have been quite limited in Korea. A recent Korean study focused on patients who visited a pri- mary care center of a university hospital (7). Although our study is not on the prevalence of CF and CFS representing the general population of Korea, we expanded the scope of subjects to patients who visited one of eight community-based primary care clinics in Korea. According to the results of this study, the prevalence of CF as serious as disabling everyday life for over 6 months was 8.4% (95% CI 7.1-9.7%), which was similar to 5-15% in foreign researches (on patients visiting primary care institutions) but was lower than 11.4% in a study in Korea on patients who visited a university hospital (3-7, 11-14). The difference might be due to different study subjects. In this study, 10 out of 1,648 subjects were found to have CFS, so the point preva- lence of CFS was 0.6% (95% CI 0.2-1.0%) and only 7.2% of CF patients had CFS. We speculate that CFS was distin- guished from most CF by the uncertainty of its cause and several characteristic symptoms including fatigue. And this point prevalence of CFS was lower than 1.22% reported by a previous study in Korea (on patients visiting a university hospital) (7). In addition, this prevalence was lower than 0.2- Table 6. Prevalence of multiple symptoms and signs in CFS case definition* of chronic fatigue subgroups according to major prob- lems associated with chronic fatigue Physical CF (n=48) Psychological CF (n=64) CFS (n=10) p value Symptoms and signs Impaired short term memory or concentration Sore throat Tender cervical or axillary lymph nodes Muscle pain Multi-joint pain without arthritis‖ Headache of a new type, pattern, or severity¶ Unrefreshing sleep** Post-exertional malaise lasting more than 24 hr 29 (61.7%) 31 (65.9%) 11 (23.4%) 27 (57.4%) 12 (25.5%) 13 (27.7%) 30 (63.8%) 34 (72.3%) 46 (71.8%) 42 (65.6%) 11 (18.7%) 34 (53.1%) 9 (14.6%) 41 (64.1%) 55 (85.9%) 40 (62.5%) ICF (n=17) 6 (35.3%) 9 (52.9%) 8 (47.1%) 12 (70.6%) 6 (35.3%) 12 (70.6%) 14 (82.4%) 14 (82.4%) 10 (100%) 6 (60.0%) 6 (60.0%) 9 (90.0%) 8 (80.0%) 9 (90.0%) 10 (100%) 10 (100%) 0.003 0.061 0.002 0.039 0.000 0.000 0.013 0.051 All symptoms and signs were lasting or repetitive for more than six months. CF, Chronic Fatigue; CFS, Chronic Fatigue Syndrome; ICF, Idiopathic Chronic Fatigue. *from Fukuda K et al. The chronic fatigue syndrome: a comprehensive approach to its definition and study. Ann Intern Med 1994; 121: 953-9. p<0.05: CFS vs. Physical CF, CFS vs. ICF, Physical CF vs. ICF, Psychological CF vs. ICF. p<0.05: CFS vs. Physical CF, CFS vs. Psycho- logical CF, Psychological CF vs. ICF. p<0.05: CFS vs. Physical CF, CFS vs. Psychological CF. ‖p<0.05: CFS vs. Physical CF, CFS vs. Psychological CF, CFS vs. ICF. ¶p<0.05: CFS vs. Physical CF, Physical CF vs. Psychological CF, Physical CF vs. ICF. **p<0.05: CFS vs. Physical CF, Physical CF vs. Psychological CF.