Table 4.
Estimated coefficients of the fitted logistic regression model for increased likelihood of current/recent infection,a before and after backward elimination
| Characteristics | Saturated model | Final model | ||
|---|---|---|---|---|
| OR (95% CI) | p-value | OR (95% CI) | p-value | |
| Age 18–29 vs. 45–59 yearsb | 0.57 (0.10–3.31) | .53 | 0.58 (0.11–3.24) | .54 |
| Age 30–44 vs. 45–59 yearsb | 1.21 (0.31–4.74) | .79 | 1.21 (0.32–4.57) | .78 |
| Age ≥60 vs. 45–59 yearsb | 3.60 (1.06–12.24) | .040 | 2.99 (0.94–9.56) | .064 |
| Male vs. female | 1.55 (0.65–3.70) | .32 | – | – |
| Vaccination yes vs. no | 2.03 (0.35–11.81) | .43 | – | – |
| Vaccination unknown vs. no | 3.31 (0.71–15.5) | .13 | – | – |
| Pertussis yes vs. no | 0.45 (0.06–3.64) | .45 | – | – |
| Pertussis unknown vs. no | 0.30 (0.08–1.08) | .065 | – | – |
| Medicationc yes vs. no | 1.24 (0.35–4.38) | .74 | – | – |
| Medicationc unknown vs. no | 2.14 (0.25–17.97) | .49 | – | – |
| Hospitalizationd yes vs. no | 0.00 (0.00–NR) | .99 | – | – |
| Hospitalizationd unknown vs. no | 0.00 (0.00–NR) | 1.00 | – | – |
| Current vs. never smoker | 7.08 (2.17–23.16) | .0012 | 7.50 (2.32–24.31) | .0008 |
| Former vs. never smoker | 4.12 (1.21–14.01) | .024 | 4.07 (1.21–13.64) | .023 |
Abbreviations: CI confidence interval, NR not reported, OD optical density, OR odds ratio, vs. versus
a≥1.0 OD units
bThe age group with the lowest seropositivity was used as the reference
cAny antibiotics and/or other medication (i.e., any cough medicines) for lower respiratory tract infections or (suspected) pertussis infections in the previous 12 months
dHospitalized due to respiratory infections in the previous 12 months