Table 4.
Crude and adjusted associations between pertussis and household contact in adults and teenagers in England
| Risk factor group | Variable | Category | Univariable associations | Multivariable models | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M1 | M4A* | M4B† | M4C‡ | ||||||||||
| uOR (95% CI) | P | aOR (95% CI) | P | aOR (95% CI) | P | aOR (95% CI) | p | χ2 (P)§ | aOR (95% CI) | P | |||
| Demographics | Age quintiles | Q1: 15–32 years | 3·20 (1·82–5·95) | <0·001 | 3·56 (1·86–6·79) | <0·001 | 2·79 (1·36–5·74) | 0·005 | — | — | — | 2·92 (1·51–5·65) | 0·001 |
| Q2: 33–43 years | 2·83 (1·52–5·28) | 0·001 | 3·23 (1·68–6·22) | <0·001 | 2·45 (1·09–5·49) | 0·029 | — | — | — | 2·33 (1·17–4·63) | 0·016 | ||
| Q3: 44–51 years | 2·24 (1·22–4·13) | 0·010 | 2·38 (1·25–4·52) | 0·008 | 1·63 (0·78–3·41) | 0·191 | — | — | — | 1·70 (0·86–3·33) | 0·125 | ||
| Q4: 52–61 years | 1·42 (0·76–2·68) | 0·278 | 1·54 (0·80–2·98) | 0·204 | 1·35 (0·68–2·71) | 0·394 | — | — | — | 1·40 (0·72–2·72) | 0·326 | ||
| Q5: 62–87 years | Ref. | — | Ref. | — | Ref. | — | — | — | — | Ref. | — | ||
| Sex | Male | 1·73 (1·15–2·60) | 0·008 | 1·84 (1·19–2·83) | 0·006 | 1·69 (1·08–2·66) | 0·022 | — | — | — | 1·81 (1·66–2·81) | 0·008 | |
| Female | Ref. | — | Ref. | — | Ref. | — | — | — | — | Ref. | — | ||
| Region | London | 2·49 (1·00–6·22) | 0·051 | 1·98 (0·76–5·11) | 0·160 | 2·08 (0·78–5·53) | 0·142 | — | — | — | 2·12 (0·81–5·55) | 0·126 | |
| South West | 2·61 (1·24–5·48) | 0·011 | 3·14 (1·43–6·94) | 0·005 | 3·05 (1·36–6·83) | 0·007 | — | — | — | 3·05 (1·37–6·79) | 0·006 | ||
| West Midlands | 1·45 (0·93–2·27) | 0·107 | 1·42 (0·89–2·26) | 0·141 | 1·53 (0·94–2·47) | 0·084 | — | — | — | 1·46 (0·91–2·34) | 0·117 | ||
| Yorkshire & the Humber | Ref. | — | Ref. | — | Ref. | — | — | — | — | Ref. | — | ||
| Travel | Recent travel | Yes | 0·76 (0·50–1·17) | 0·222 | 0·67 (0·41–1·07) | 0·094 | 0·71 (0·44–1·15) | 0·166 | — | — | — | 0·66 (0·41–1·06) | 0·085 |
| Household contacts | ⩾1 child or young adult | <1 year | 3·12 (0·86–11·34) | 0·084 | — | — | 8·17 (0·99–67·36) | 0·051 | 2·72 (0·57–12·97) | 0·209 | 2·20 (0·14) | not included | — |
| 1–4 years | 0·86 (0·42–1·76) | 0·687 | — | — | 1·34 (0·33–5·46) | 0·682 | 0·66 (0·29–1·48) | 0·308 | 0·96 (0·327) | not included | — | ||
| 5–9 years | 1·38 (0·82–2·13) | 0·256 | — | — | 2·48 (0·47–13·12) | 0·287 | 0·96 (0·50–1·86) | 0·913 | 0·14 (0·704) | not included | — | ||
| Young children (⩽9 years) | 1·32 (0·82–2·13) | 0·257 | — | — | 0·46 (0·07–2·98) | 0·416 | 0·87 (0·48–1·60) | 0·646 | 0·54 (0·461) | not included | — | ||
| 10–14 years | 3·25 (1·92–5·50) | <0·001 | — | — | 1·90 (0·74–4·87) | 0·180 | 2·61 (1·47–4·64) | 0·001 | 11·43 (<0·001) | 2·61 (1·47–4·64) | 0·001 | ||
| 15–19 years | 1·50 (0·93–2·42) | 0·094 | — | — | 0·91 (0·35–2·36) | 0·842 | 1·34 (0·79–2·28) | 0·272 | 0·74 (0·390) | not included | — | ||
| 20–21 years | 1·98 (0·75–5·25) | 0·171 | — | — | 1·22 (0·37–3·98) | 0·744 | 1·41 (0·50–3·94) | 0·514 | 0·61 (0·433) | not included | — | ||
| Older children (10–21 years) | 2·55 (1·68–3·85) | <0·001 | — | — | 2·71 (0·65–11·32) | 0·173 | 2·09 (1·30–3·36) | 0·002 | 1·63 (0·201) | not included | — | ||
| Any age (0–21 years) | 1·93 (1·31–2·85) | 0·001 | — | — | 0·47 (0·13–1·71) | 0·253 | 1·49 (0·92–2·43) | 0·107 | 0·02 (0·902) | not included | — | ||
| Household size | ⩽2 | Ref. | — | — | — | Ref. | — | Ref. | — | — | — | — | |
| ⩾3 | 1·94 (1·31–2·86) | 0·001 | — | — | 1·09 (0·55–2·14) | 0·805 | 1·40 (0·87–2·25) | 0·160 | 0·16 (0·694) | not included | — | ||
uOR, Unadjusted odds ratio; CI, confidence interval; aOR, adjusted odds ratio; Q1–Q5, quintiles 1–5; Ref., reference group.
Values in bold indicate statistical significance (P < 0·05).
All professional contact with children or young adult variables added simultaneously to M1.
A separate model produced for each professional contact with children or young adult variable added to M1.
Variables added to M1 in order of increasing statistical significance according to P value from M3B, variables retained only if the lead to a statistically significant improvement in fit.
χ2 and associated P value of the likelihood ratio test of improved fit compared to M1.