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Table 1 Descriptive characteristics of the study population

From: Subjective cognitive decline and subsequent dementia: a nationwide cohort study of 579,710 people aged 66 years in South Korea

 Total (n = 579,710)Non-SCD group (n = 357,654)SCD group (n = 222,056)P value
Sex   < 0.0001
 Male266,311 (45.9%)173,795 (48.6%)92,516 (41.7%) 
 Female313,399 (54.1%)183,859 (51.4%)129,540 (58.3%) 
Income   < 0.0001
 Medicaid aid33,023 (5.7%)19,101 (5.3%)13,922 (6.3%) 
 Group 1 (1st to 6th ventiles)125,064 (21.6%)82,491 (23.1%)42,573 (19.2%) 
 Group 2 (7th to 14th ventiles)178,625 (30.8%)110,550 (30.9%)68,075 (30.7%) 
 Group 3 (15th to 20th ventiles)242,998 (41.9%)145,512 (40.7%)97,486 (43.9%) 
Lifestyle factors
 Smoking status   < 0.0001
  Never smoked406,103 (70.1%)250,238 (70.0%)155,865 (70.2%) 
  Ex-smoker95,502 (16.5%)57,647 (16.1%)37,855 (17.0%) 
  Current smoker78,105 (13.5%)49,769 (13.9%)28,336 (12.8%) 
 Alcohol consumption   < 0.0001
  No drinking: rarely508,547 (87.7%)314,324 (87.9%)194,223 (87.5%) 
  Light drinking: 3–4 times per week38,840 (6.7%)23,954 (6.7%)14,886 (6.7%) 
  Heavy drinking: almost every day32,323 (5.6%)19,376 (5.4%)12,947 (5.8%) 
 Exercise frequency   < 0.0001
  Exercise327,775 (56.5%)200,723 (56.1%)127,052 (57.2%) 
  No exercise251,935 (43.5%)156,931 (43.9%)95,004 (42.8%) 
Healthcare visit frequency*
 First quartile144,858 (25.0%)93,542 (26.2%)51,316 (23.1%) 
 Second quartile144,945 (25.0%)89,583 (25.1%)55,362 (24.9%) 
 Third quartile144,988 (25.0%)88,208 (24.7%)56,780 (25.6%) 
 Fourth quartile144,919 (25.0%)86,321 (24.1%)58,598 (26.4%) 
Past medical history
 Psychiatric disorders
  Depression48,653 (8.4%)26,676 (7.5%)21,977 (9.9%)< 0.0001
  Bipolar affective disorder1891 (0.3%)1059 (0.3%)832 (0.4%)< 0.0001
  Substance use disorder3522 (0.6%)2035 (0.6%)1487 (0.7%)< 0.0001
  Panic disorder2315 (0.4%)1298 (0.4%)1017 (0.5%)< 0.0001
  Obsessive-compulsive disorder671 (0.1%)370 (0.1%)301 (0.1%)0.001
  Personality disorder237 (0.0%)142 (0.0%)95 (0.0%)0.619
  Other psychiatric disorders140,212 (24.2%)81,764 (22.9%)58,448 (26.3%)< 0.0001
 Neurological diseases
  Cerebrovascular disease80,212 (13.8%)46,895 (13.1%)33,317 (15.0%)< 0.0001
  Epilepsy8622 (1.5%)4807 (1.3%)3815 (1.7%)< 0.0001
  Migraines43,466 (7.5%)25,304 (7.1%)18,162 (8.2%)< 0.0001
  Headaches70,207 (12.1%)40,791 (11.4%)29,416 (13.2%)< 0.0001
  Sleep disorder63,769 (11.0%)36,635 (10.2%)27,134 (12.2%)< 0.0001
  Head injury64,698 (11.2%)39,459 (11.0%)25,239 (11.4%)< 0.0001
 Medical diseases
  Diabetes mellitus154,977 (26.7%)94,346 (26.4%)60,631 (27.3%)< 0.0001
  Myocardial infarction8504 (1.5%)5245 (1.5%)3259 (1.5%)0.981
  Congestive heart failure31,952 (5.5%)19,222 (5.4%)12,730 (5.7%)< 0.0001
  Liver disease146,020 (25.2%)88,392 (24.7%)57,628 (26.0%)< 0.0001
  Renal disease5669 (1.0%)3476 (1.0%)2193 (1.0%)0.564
  Peptic ulcer disease259,797 (44.8%)155,929 (43.6%)103,868 (46.8%)< 0.0001
  Thyroid gland disorder40,236 (6.9%)23,104 (6.5%)17,132 (7.7%)< 0.0001
  Asthma123,850 (21.4%)74,598 (20.9%)49,252 (22.2%)< 0.0001
  Cancer41,290 (7.1%)24,845 (6.9%)16,445 (7.4%)< 0.0001
 Medication history
  HMG-CoA reductase inhibitors128,527 (22.2%)77,725 (21.7%)50,802 (22.9%)< 0.0001
  Diabetes medication84,015 (14.5%)51,878 (14.5%)32,137 (14.5%)0.735
  Antihypertensive medication288,262 (49.7%)178,093 (49.8%)110,169 (49.6%)0.180
  Antidepressants31,079 (5.4%)17,216 (4.8%)13,863 (6.2%)< 0.0001
  Benzodiazepines and sleeping pills92,444 (15.9%)53,108 (14.8%)39,336 (17.7%)< 0.0001
  Antiplatelet medication140,615 (24.3%)86,071 (24.1%)54,544 (24.6%)< 0.0001
 Depression Screening Questionnaire score, mean (SD)0.34 (0.79)0.23 (0.67)0.53 (0.92)< 0.0001
Laboratory findings
 Cholesterol level, mean (SD), mg/dL
  LDL cholesterol117.47 (35.58)117.26 (35.55)117.81 (35.64)< 0.0001
  HDL cholesterol53.63 (13.64)53.57 (13.61)53.73 (13.68)< 0.0001
  Triglycerides134.31 (70.64)134.80 (70.97)133.54 (70.10)< 0.0001
  Fasting glucose101.89 (20.96)102.11 (21.10)101.52 (20.73)< 0.0001
  Hemoglobin13.59 (1.40)13.63 (1.40)13.54 (1.39)< 0.0001
 Physical examination findings
  Body mass index24.29 (2.98)24.31 (2.99)24.25 (2.98)< 0.0001
  Systolic blood pressure128.74 (15.43)129.05 (15.44)128.22 (15.41)< 0.0001
  Diastolic blood pressure78.01 (9.73)78.18 (9.73)77.73 (9.73)< 0.0001
  1. HDL high-density lipoprotein, LDL low-density lipoprotein, SCD subjective cognitive decline, SD standard deviation
  2. *The fourth quartile group had the highest frequency of medical visits