Volume 14, Number 6—June 2008
Research
Population-Attributable Risk Estimates for Risk Factors Associated with Campylobacter Infection, Australia
, Philip J. Schluter‡†, Andrew J. Wilson*†, Martyn D. Kirk§, Gillian Hall¶, Leanne Unicomb¶#, and the OzFoodNet Working Group
Table 1
Results of univariable (crude) and multivariable logistic regression analysis for variables within each exposure group and the final multivariable model, Campylobacter infection, Australia, 2001–2002*
| Exposure group/variables† | Case-patients, n/N (%) | Controls, n/N (%) | Univariable analysis | Multivariable logistic regression analysis (exposure groups) | Final multivariable model‡ | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| OR | 95% CI | OR | 95% CI | aOR | 95% CI | |||||
| Meat, poultry and seafood | Model 1 | |||||||||
| No chicken | 110/711 (15.5) | 162/808 (20.0) | 1.0 | 1.0 | 1.0 | |||||
| Chicken, cooked | 528/711 (74.3) | 618/808 (76.5) | 1.3 | 1.0–1.7 | 1.3 | 1.0–1.8 | 1.4 | 1.0– 1.9 | ||
| Chicken, undercooked | 73/711 (10.3) | 28/808 (3.5) | 3.8 | 2.3–6.3 | 4.4 | 2.6–7.5 | 4.7 | 2.6– 8.4 | ||
| Offal | 36/852 (4.2) | 16/830 (1.9) | 2.2 | 1.2–4.4 | 2.1 | 1.1–3.9 | 2.0 | 1.0– 4.0 | ||
| Fresh fish | 256/833 (30.7) | 332/827 (40.1) | 0.7 | 0.5–0.8 | 0.6 | 0.5–0.8 | 0.7 | 0.5– 0.9 | ||
| Eggs and dairy products | Model 2 | |||||||||
| Homemade foods containing raw eggs | 40/837 (4.8) | 70/822 (8.5) | 0.5 | 0.4–0.8 | 0.5 | 0.3–0.7 | 0.5 | 0.3– 0.8 | ||
| Produce | Model 3 | |||||||||
| Organic fruit and vegetables | 50/805 (6.2) | 100/804 (12.4) | 0.5 | 0.3–0.7 | 0.6 | 0.4–0.8 | 0.6 | 0.4–1.0 | ||
| Homegrown fruit | 84/845 (9.9) | 169/828 (20.4) | 0.4 | 0.3–0.6 | 0.5 | 0.4–0.7 | 0.4 | 0.3–0.6 | ||
| Vegetable index§ | ||||||||||
| 0 (no vegetables) | 141/853 (16.5) | 87/830 (10.5) | 1.0 | 1.0 | 1.0 | |||||
| 1 (1–2) | 339/853 (39.7) | 305/830 (36.7) | 0.7 | 0.5–0.9 | 0.7 | 0.5–1.0 | 0.7 | 0.5–1.0 | ||
| 2 (3–4) | 352/853 (41.3) | 382/830 (46.0) | 0.6 | 0.4–0.8 | 0.6 | 0.4–0.9 | 0.6 | 0.4–0.9 | ||
| 3 (5–6) | 21/853 (2.5) | 56/830 (6.7) | 0.2 | 90.1–0.4 | 0.3 | 0.1–0.5 | 0.2 | 0.1–0.5 | ||
| Water consumption | Model 4 | |||||||||
| Commercial bottled water | 72/846 (8.5) | 47/820 (5.7) | 1.5 | 1.0–2.3 | 1.6 | 1.1–2.3 | NS | |||
| Food-handling practices | Model 5 | |||||||||
| Barbequed cooked meat
placed back on plate used
for raw meat | 21/511 (4.1) | 9/471 (1.9) | 2.2 | 1.0–5.5 | 2.3 | 1.0–5.4 | NS | |||
| Animal and pet exposure | ||||||||||
| Domestic chickens | Model 6 | |||||||||
| No domestic chicken | 783/846 (92.6) | 777/821 (94.6) | 1.0 | 1.0 | 1.0 | |||||
| Chicken <6 mo of age | 18/846 (2.1) | 5/821 (0.6) | 3.6 | 1.3–9.7 | 5.2 | 1.5–17.8 | 12.4 | 2.6– 59.3 | ||
| Chicken >6 mo of age | 45/846 (5.3) | 39/821 (4.8) | 1.1 | 0.7–1.8 | 1.3 | 0.8–2.2 | 1.7 | 0.9– 3.0 | ||
| Domestic dogs | ||||||||||
| No dog | 397/839 (47.3) | 452/819 (55.2) | 1.0 | 1.0 | 1.0 | |||||
| Dog <6 mo of age | 48/839 (5.7) | 17/819 (2.1) | 3.2 | 1.8–5.7 | 2.9 | 1.6–5.3 | 2.1 | 1.1– 4.2 | ||
| Dog >6 mo of age | 394/839 (47.0) | 350/819 (42.7) | 1.3 | 1.1–1.6 | 1.2 | 1.0–1.5 | 1.2 | 0.9–1.5 | ||
| Host factors | Model 7 | |||||||||
| Chronic gastrointestinal condition | 101/873 (11.6) | 50/831 (6.0) | 2.0 | 1.4–3.0 | 2.0 | 1.4–2.9 | 2.3 | 1.5–3.4 | ||
| Liver disease | 14/875 (1.6) | 2/830 (0.2) | 6.7 | 1.5–61.2 | 5.1 | 1.1–23.0 | NS | |||
| Any immunosuppressive agent/therapy | 35/881 (4.0) | 12/833 (1.4) | 2.8 | 1.4–6.0 | 2.8 | 1.4–5.5 | NS | |||
*Each model adjusted for state, sex, and education. aOR, adjusted odds ratio; CI, confidence interval; NS, not significant.
†The exposure period for foods is 7 d before onset of illness for case-patients and 7 days before interview for controls.
‡After removal of nonsignificant interaction terms.
§The vegetable index was created to indirectly measure the range of raw produce consumed in the 7-day exposure period for patients and controls. The values of this index variable represented a count of the number of different types of salad/vegetable foods eaten during the exposure period.