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Table 3 Adjusted odds ratios of factors associated with LTC certification before and after variable selection

From: Factors associated with long-term care certification in older adults: a cross-sectional study based on a nationally representative survey in Japan

  Model 1a Model 1Ab Model 2c
Odds ratio (95% CI) P-value Odds ratio (95% CI) P-value Odds ratio (95% CI) P-value
Intercept 0.02 (0.01–0.03) < 0.001 0.02 (0.01–0.02) < 0.001 0.02 (0.01–0.03) < 0.001
Predisposing factors
 Sex (women vs men) 0.79 (0.50–1.25) 0.320 0.78 (0.50–1.23) 0.291 0.74 (0.48–1.15) 0.184
 Age, years (vs 65–69)
  70–74 1.93 (1.29–2.89) 0.001 1.97 (1.32–2.93) < 0.001 2.05 (1.40–3.00) < 0.001
  75–79 1.88 (1.24–2.84) 0.003 1.90 (1.26–2.85) 0.002 2.29 (1.56–3.36) < 0.001
  80–84 4.58 (3.08–6.79) < 0.001 4.57 (3.09–6.76) < 0.001 5.57 (3.86–8.03) < 0.001
  85–89 6.43 (4.14–9.98) < 0.001 6.40 (4.14–9.89) < 0.001 7.75 (5.19–11.56) < 0.001
  ≥ 90 20.61 (11.99–35.44) < 0.001 20.59 (12.00–35.33) < 0.001 19.93 (12.07–32.91) < 0.001
 Interaction age × sexd
  Women ×  70–74 0.94 (0.53–1.67) 0.832 0.92 (0.52–1.63) 0.783 0.87 (0.50–1.50) 0.614
  Women ×  75–79 1.28 (0.72–2.25) 0.400 1.29 (0.73–2.26) 0.377 1.20 (0.71–2.04) 0.497
  Women ×  80–84 1.21 (0.70–2.07) 0.493 1.21 (0.71–2.08) 0.479 1.07 (0.64–1.77) 0.804
  Women × 85–89 2.49 (1.41–4.41) 0.002 2.49 (1.41–4.39) 0.002 2.32 (1.37–3.94) 0.002
  Women × ≥ 90 1.67 (0.86–3.23) 0.128 1.64 (0.85–3.16) 0.142 1.81 (0.98–3.36) 0.060
  Education level (>9 vs ≤ 9 years) 0.86 (0.73–1.01) 0.067 0.87 (0.74–1.01) 0.073 0.85 (0.74–0.98) 0.025
Enabling factors
 Equivalent disposable incomee 1.00 (0.85–1.17) 0.982    1.01 (0.87–1.16) 0.924
 (≥ ¥100,000 vs < ¥100,000)
 Type of housing (rented vs owned) 1.18 (0.99–1.41) 0.071 1.21 (1.02–1.44) 0.030 1.24 (1.05–1.45) 0.010
 Presence of a spouse (yes vs no) 0.42 (0.35–0.49) < 0.001 0.42 (0.36–0.50) < 0.001 0.48 (0.41–0.55) < 0.001
 Household structure 0.91 (0.78–1.06) 0.213    1.02 (0.89–1.17) 0.795
 (Others vs single or couple-only)
 Presence of children living separately (yes vs no) 1.21 (1.04–1.41) 0.015 1.23 (1.06–1.42) 0.007 1.22 (1.06–1.40) 0.006
Need factors
 Subjective symptoms
 Number of symptoms (≥3 vs 0–2)      1.31 (1.14–1.51) < 0.001
  Fever 1.15 (0.60–2.21) 0.665     
  Lethargic 0.84 (0.63–1.11) 0.208     
  Do not sleep well 1.33 (1.02–1.74) 0.038 1.35 (1.05–1.75) 0.021   
  Irritable 0.97 (0.66–1.41) 0.854     
  Forgetful 0.79 (0.63–0.98) 0.036 0.80 (0.65–0.99) 0.043   
  Headache 1.12 (0.78–1.61) 0.529     
  Dizziness 1.05 (0.77–1.45) 0.745     
  Blurred vision 0.87 (0.70–1.10) 0.250     
  Difficulty in seeing 1.15 (0.90–1.46) 0.257     
  Ringing ears 0.72 (0.53–0.97) 0.029 0.71 (0.53–0.95) 0.022   
  Difficulty in hearing 0.85 (0.68–1.06) 0.147 0.86 (0.69–1.06) 0.152   
  Palpitations 0.78 (0.56–1.10) 0.163 0.78 (0.56–1.08) 0.139   
  Short-winded 0.75 (0.54–1.04) 0.084 0.77 (0.56–1.06) 0.109   
  Pain in chest 0.78 (0.49–1.24) 0.293     
  Cough, phlegmatic 1.48 (1.15–1.89) 0.002 1.46 (1.15–1.86) 0.002   
  Blocked/runny nose 0.82 (0.60–1.12) 0.215 0.81 (0.60–1.09) 0.165   
  Wheezing 1.52 (1.00–2.28) 0.048 1.48 (1.00–2.18) 0.051   
  Stomach upset/heartburn 0.73 (0.51–1.05) 0.094 0.74 (0.52–1.04) 0.086   
  Diarrhoea 2.04 (1.38–3.00) < 0.001 2.15 (1.48–3.13) < 0.001   
  Constipation 0.90 (0.72–1.14) 0.392     
  Loss of appetite 1.27 (0.87–1.85) 0.223     
  Abdominal pain/stomachache 1.13 (0.72–1.77) 0.594     
  Painful/bleeding hemorrhoids 1.29 (0.78–2.13) 0.326     
  Toothache 0.82 (0.53–1.26) 0.364     
  Swollen/bleeding gums 1.14 (0.77–1.67) 0.517     
  Difficulty in chewing 1.18 (0.90–1.54) 0.238     
  Rash 0.87 (0.54–1.40) 0.558     
  Itching 1.05 (0.80–1.39) 0.705     
  Joint pain in hands/feet 0.90 (0.73–1.11) 0.313     
  Difficulty in limb movement 2.07 (1.70–2.53) < 0.001 2.08 (1.72–2.51) < 0.001   
  Numb limbs 1.35 (1.08–1.69) 0.008 1.34 (1.08–1.67) 0.007   
  Cold limbs 1.04 (0.80–1.34) 0.783     
  Swollen/heavy feet 1.42 (1.12–1.80) 0.004 1.43 (1.13–1.79) 0.002   
  Difficulty in/painful urination 1.00 (0.68–1.48) 0.988     
  Frequent urination 1.12 (0.89–1.42) 0.336     
  Incontinence 1.61 (1.23–2.11) < 0.001 1.61 (1.24–2.09) < 0.001   
  Injury including cut, burn 0.60 (0.28–1.29) 0.195     
 Regular hospital visits (yes vs no)
 Number of diseases (≥3 vs 0–2)      1.47 (1.28–1.69) < 0.001
  Diabetes 1.60 (1.31–1.96) < 0.001 1.60 (1.32–1.96) < 0.001   
  Obesity 0.65 (0.30–1.40) 0.270 0.60 (0.28–1.28) 0.187   
  Hyperlipidemia 0.95 (0.73–1.23) 0.686     
  Thyroid disease 0.94 (0.58–1.51) 0.794     
  Mental illness 1.42 (0.90–2.24) 0.132 1.40 (0.90–2.20) 0.138   
  Dementia 14.62 (11.05–19.35) < 0.001 14.34 (10.87–18.93) < 0.001   
  Parkinson’s disease 4.37 (2.54–7.51) < 0.001 4.15 (2.42–7.11) < 0.001   
  Other nervous disorders 2.57 (1.69–3.89) < 0.001 2.49 (1.65–3.76) < 0.001   
  Eye disease 0.78 (0.64–0.95) 0.016 0.78 (0.64–0.94) 0.010   
  Ear disease 0.75 (0.49–1.14) 0.181 0.75 (0.49–1.14) 0.176   
  Hypertension 0.66 (0.57–0.77) < 0.001 0.66 (0.57–0.77) < 0.001   
  Stroke 6.90 (5.48–8.67) < 0.001 6.90 (5.49–8.65) < 0.001   
  Ischemic heart disease 1.12 (0.86–1.45) 0.392     
  Other circulatory diseases 0.90 (0.67–1.20) 0.466     
  Cold 0.59 (0.21–1.63) 0.305     
  Allergic rhinitis 0.77 (0.45–1.32) 0.334     
  COPD 3.44 (1.65–7.18) 0.001 3.51 (1.69–7.30) < 0.001   
  Asthma 1.04 (0.64–1.71) 0.865     
  Other respiratory diseases 1.62 (1.11–2.38) 0.013 1.55 (1.06–2.26) 0.022   
  Stomach/duodenum disease 0.63 (0.43–0.93) 0.020 0.67 (0.46–0.98) 0.040   
  Liver/gall bladder disease 1.34 (0.89–2.01) 0.167     
  Other digestive diseases 1.08 (0.73–1.62) 0.691     
  Dental diseases 0.54 (0.38–0.76) < 0.001 0.55 (0.40–0.76) < 0.001   
  Atopic dermatitis 1.51 (0.60–3.80) 0.381     
  Other skin disease 1.40 (0.93–2.11) 0.104 1.43 (0.98–2.09) 0.063   
  Gout 0.71 (0.35–1.44) 0.347     
  Rheumatoid arthritis 2.66 (1.78–3.98) < 0.001 2.58 (1.74–3.81) < 0.001   
  Arthropathy 1.05 (0.80–1.38) 0.711     
  Stiff shoulder 0.60 (0.43–0.83) 0.002 0.61 (0.45–0.83) 0.001   
  Low back pain 1.02 (0.83–1.26) 0.851     
  Osteoporosis 1.37 (1.08–1.75) 0.011 1.39 (1.09–1.76) 0.007   
  Kidney disease 2.16 (1.53–3.06) < 0.001 2.22 (1.59–3.11) < 0.001   
  Prostatic hyperplasia 1.26 (0.90–1.78) 0.182 1.31 (0.94–1.83) 0.108   
  Menopause or postmenopausal disorders 2.04 (0.25–16.40) 0.501     
  Fracture 2.96 (2.03–4.29) < 0.001 2.85 (1.97–4.13) < 0.001   
  Injury other than fracture/burn 1.35 (0.69–2.61) 0.378     
  Anemia/blood disorder 1.34 (0.82–2.19) 0.236     
  Cancer 0.94 (0.54–1.63) 0.828     
 Consult about worries and stress with (yes vs no)
  Family 1.66 (1.40–1.97) < 0.001 1.65 (1.40–1.95) < 0.001 1.65 (1.42–1.93) < 0.001
  Friends/acquaintances 0.69 (0.53–0.90) 0.006 0.69 (0.53–0.90) 0.005 0.66 (0.52–0.84) < 0.001
  Boss at work/teacher at school 2.47 (0.29–21.17) 0.409    1.81 (0.29–11.32) 0.525
  Public institutions 3.36 (2.43–4.64) < 0.001 3.31 (2.40–4.55) < 0.001 3.70 (2.79–4.89) < 0.001
  Doctors 1.54 (1.28–1.85) < 0.001 1.52 (1.27–1.82) < 0.001 1.94 (1.65–2.28) < 0.001
  Other than above 1.38 (0.92–2.05) 0.115 1.41 (0.95–2.08) 0.085 1.57 (1.10–2.22) 0.012
  Cannot consult anyone 1.26 (0.75–2.11) 0.382    1.35 (0.85–2.12) 0.201
  Do not know where to consult 1.26 (0.68–2.34) 0.460    1.21 (0.70–2.08) 0.496
  No need to consult 0.99 (0.75–1.31) 0.959    1.01 (0.78–1.31) 0.938
 K6 total score (≥13 vs < 13) 1.76 (1.32–2.36) < 0.001 1.83 (1.38–2.43) < 0.001 2.56 (2.01–3.26) < 0.001
  1. Abbreviations: LTC long-term care, CI confidence interval, COPD chronic obstructive pulmonary disease
  2. aModel1 before variable selection
  3. bModel1A after variable selection
  4. cModel2 Subjective symptoms and regular hospital visits were clustered into ≥3 or 0–2 symptoms/diseases
  5. dInteraction term between sex and age groups
  6. eThe disposable income of a household divided by the square root of the number of people in the household