Zero inflation model of number of hospitalisations within a 10-year period of entering the study
| Variable | 0 diseases (ref) | Zero inflation model | |||||
| Binary part* | Count part† | ||||||
| OR | 95% CI | P value | Risk ratio | 95% CI | P value | ||
| Count of morbidities | |||||||
| 1 disease | 0.73 | (0.67 to 0.80) | <0.001 | 1.24 | (1.18 to 1.31) | <0.001 | |
| 2 diseases | 0.57 | (0.52 to 0.63) | <0.001 | 1.53 | (1.45 to 1.62) | <0.001 | |
| 3 diseases | 0.51 | (0.45 to 0.58) | <0.001 | 1.70 | (1.59 to 1.80) | <0.001 | |
| 4+ diseases | 0.36 | (0.31 to 0.42) | <0.001 | 2.01 | (1.88 to 2.17) | <0.001 | |
| Sex | Females (ref) | ||||||
| Males | – | – | – | 1.03 | (0.99 to 1.07) | 0.05 | |
| Age | Age at entrance | 0.96 | (0.95 to 0.96) | <0.001 | 1.01 | (1.01 to 1.01) | <0.001 |
| Education | No-education (ref) | ||||||
| Education | 1.22 | (1.13 to 1.31) | <0.001 | 0.95 | (0.91 to 0.99) | 0.01 | |
| Wealth quintiles | Wealth quintile 1 (ref) | ||||||
| Wealth quintile 2 | 0.89 | (0.82 to 0.97) | 0.007 | – | – | – | |
| Wealth quintile 3 | 0.89 | (0.82 to 0.96) | 0.003 | – | – | – | |
| Wealth quintile 4 | 0.86 | (0.80 to 0.94) | <0.001 | – | – | – | |
| Wealth quintile 5 | 0.86 | (0.79 to 0.95) | <0.001 | – | – | – | |
| Ethnicity | Turkmen (ref) | ||||||
| Not Turkmen | 0.76 | (0.70 to 0.81) | <0.001 | 1.15 | (1.11 to 1.20) | <0.001 | |
| Smoking status | Never smoked (ref) | ||||||
| Current/ex-smoker | 0.86 | (0.79 to 0.94) | <0.001 | 1.07 | (1.02 to 1.12) | 0.001 | |
| BMI | BMI <18.5 or ≥25 (ref) | ||||||
| BMI: 18.5≤x<25 | 1.16 | (1.08 to 1.24) | <0.001 | – | – | – | |
| BMI | BMI <25(ref) | ||||||
| BMI: ≥25 | – | – | – | 1.11 | (1.07 to 1.16) | <0.001 | |
| Physical activity | Physical activity 1 (ref) | ||||||
| Physical activity 2 | 1.20 | (1.13 to 1.28) | <0.001 | – | – | – | |
| Physical activity 3 | 1.24 | (1.15 to 1.35) | <0.001 | – | – | – | |
| Physical activity | Physical activity 1–2 (ref) | ||||||
| Physical activity 3 | – | – | – | 0.93 | (0.89 to 0.97) | <0.001 | |
The following changes were made through backwards elimination.
Area of living and marital status were excluded from both models due to insignificance.
Sex was not a significant predictor of the outcome in the binary part of the model and was therefore excluded.
Wealth was not a significant predictor of the outcome in the count part of the model and was therefore excluded; BMI categories were changed to BMI 18.5–25 vs not for the binary part and <25 vs not for the count part.
Physical activity categories were changed to 1–2 vs 3 for the count part.
The zero inflation (binary) part shows ORs of how variables affect a participant being in the inflated zero-hospitalisations group, then a count model is fitted to show risk ratios for the number of hospitalisations which occur if a participant could have more than 0 hospitalisations.
*Predicting if a participant had certainly 0 hospitalisations in study period.
†Number of times of hospitalisations, if participant did not have certainly 0 hospitalisations.
BMI, body mass index.