In a multicenter prospective casecontrol study involv - PDF document

In 2001–2002, a multicenter, prospective case-control ducted in Australia to identify risk factors for infection. Adjusted population-attributable risks (PARs) were nal multivariable logistic regression model. Estimated P�ARs were combined with adjusted (for the 5 years of age Population-Attributable Risk Estimates for Risk Factors Associated with *Queensland Health, Brisbane, Queensland, Australia; †Univer-sity of Queensland, Brisbane; ‡Auckland University of Technology, Auckland, New Zealand; §OzFoodNet, Canberra, Australian Capi-tal Territory, Australia; ¶Australian National University, Canberra; #OzFoodNet, Wallsend, New South Wales, Australia In addition to some of the authors, the OzFoodNet Working Group for this study included Craig Dalton, Tony Merritt, Rosie Ashbolt, Cameron Sault, Joy Gregory, Robert Bell, Rod Givney, Nola Tomaska, Geoff Millard, Mohinder Sarna, Geoff Hogg, Craig Williams, Janet Li, Karin Lalor, Nittita Prasopa-Plazier, Lyn Mueleners, and Ian McKay. RESEARCH � infection in persons 5 �ned as a person 5 years of age infection and a recent history of acute diarrhea, ed as the index patient. Controls were sourced from a na- rst by determining a parsimonious multivariable model cant expo- nal multivariable logistic regression cantly associated dence intervals (CIs) around the PAR estimates. Using infections attributable c risk factors that occur in the community each gure by reviewing Aus- cation data for the years 2001 through 2003 �proportion of cases that occur among persons 5 years of nal model. infections c risk factor. Because some dis- ned to be the 2.5 and 97.5 percentiles) for the simula- nal multivariable logistic regres-Multivariable Analysis of Risk Factors nal multivariable model showing frequency ed in the nal model explained 896 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 14, No. 6, June 2008 Infection, Australia = 0.16). sh, eating homemade cant Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 14, No. 6, June 2008 897 Table 1. Results of univariable (crude) and multivariable logistic regression analysis for variables within each exposure group and the Campylobacter infection, Australia, 2001–2002* analysis regression analysis (exposure groups) Exposure group/variables† n/N (%) n/N (%) OR95% CI OR95% CI aOR95% CI Meat, poultry and seafood Model 1 No chicken 110/711 (15.5) 162/808 (20.0) 1.01.01.0 Chicken, cooked 528/711 (74.3) 618/808 (76.5) 1.31.0–1.71.31.0–1.81.41.0– 1.9 Chicken, undercooked 73/711 (10.3) 28/808 (3.5) 3.82.3–6.34.42.6–7.54.72.6– 8.4 Offal 36/852 (4.2) 16/830 (1.9) 2.21.2–4.42.11.1–3.92.01.0– 4.0 Fresh fish 256/833 (30.7) 332/827 (40.1) 0.70.5–0.80.60.5–0.80.70.5– 0.9 Eggs and dairy products Homemade foods containing raw eggs 40/837 (4.8) 70/822 (8.5) 0.50.4–0.80.50.3–0.70.50.3– 0.8 Model3 Organic fruit and vegetables 50/805 (6.2) 100/804 (12.4) 0.50.3–0.70.60.4–0.80.60.4–1.0 Homegrown fruit 84/845 (9.9) 169/828 (20.4) 0.40.3–0.60.50.4–0.70.40.3–0.6 Vegetable index§ 0 (no vegetables) 141/853 (16.5) 87/830 (10.5) 1.01.01.0 1 (1–2) 339/853 (39.7) 305/830 (36.7) 0.70.5–0.90.70.5–1.00.70.5–1.0 2 (3–4) 352/853 (41.3) 382/830 (46.0) 0.60.4–0.80.60.4–0.90.60.4–0.9 3 (5–6) 21/853 (2.5) 56/830 (6.7) 0.290.1–0.40.30.1–0.50.20.1–0.5 Commercial bottled water 72/846 (8.5) 47/820 (5.7) 1.51.0–2.31.61.1–2.3NSFood-handling practices Barbequed cooked meat placed back on plate used for raw meat 21/511 (4.1) 9/471 (1.9) 2.21.0–5.52.31.0–5.4NSAnimal and pet exposure Domestic chickens No domestic chicken 783/846 (92.6) 777/821 (94.6) 1.01.01.0 Chicken 18/846 (2.1) 5/821 (0.6) 3.61.3–9.75.21.5–17.812.42.6– 59.3 Chicken  mo;&#x of ; ge ;&#x -28;H.5; 6 mo of age 45/846 (5.3) 39/821 (4.8) 1.10.7–1.81.30.8–2.21.70.9– 3.0 Domestic dogs No dog 397/839 (47.3) 452/819 (55.2) 1.01.01.0 Dog e 48/839 (5.7) 17/819 (2.1) 3.21.8–5.72.91.6–5.32.11.1– 4.2 Dog  mo;&#x of ; g-7;&#x.800; 6 mo of age 394/839 (47.0) 350/819 (42.7) 1.31.1–1.61.21.0–1.51.20.9–1.5 Chronic gastrointestinal condition 101/873 (11.6) 50/831 (6.0) 2.01.4–3.02.01.4–2.92.31.5–3.4 Liver disease 14/875 (1.6) 2/830 (0.2) 6.71.5–61.25.11.1–23.0NS Any immunosuppressive agent/therapy 35/881 (4.0) 12/833 (1.4) 2.81.4–6.02.81.4–5.5NS*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. RESEARCH nal model dur- cant. There was no reason to suspect the adequacy nal multivariable model (Hosmer-Lemeshow good- t test, p = 0.98). Additional statistical information, cients, standard errors, statistical signi t statistics for all multivari-PAR Proportions illness in the infection could g- through either improved on- gures justify the continued need for government infection have calculated PARs of independent 898 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 14, No. 6, June 2008 Table 2. PAR proportions with 95% CIs and community estimates with 95% CrIs for exposures associated with an increased risk for 5 y of age, Australia, 2001–2002*† PAR, % 95% CI community 95% CrI Food exposures Chicken consumption No chicken 1100.155Reference Chicken, cooked 5280.7431.421.20.0–36.935,5000–83,500 Chicken, undercooked 730.1034.78.15.2–11.115,0006,000–26,500 Offal consumption No 8160.958Reference Yes 360.0422.02.10.0–4.93,50050–8,500Nonfood exposures Dogs (domestic) No dog 3970.473Reference Dog e 480.0572.12.90.3–4.85,000500–11,500 Dog 6 mo of age 3940.471.2– Chickens (domestic) No domestic chickens 7830.926Reference Chickens 180.02112.41.90.9–2.93,5001,000–7,000 Chickens 450.0531.7–*PAR, population-attributable risk; CI, confidence interval; CrI, credible interval. †Calculated from adjusted odds ratios (aOR) derived from the final multivariable logistic regression model. Infection, Australia c infection may cant foodborne attributable risk estimate found in infection ( cantly associated with value of 16% for the nal most parsimonious multivari- cation of ed infection ( c risk factor in a popu- ed pathogens in stool samples submitted to × Ps × P × P ned methods for calculating rmed cases in our study is not repre- Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 14, No. 6, June 2008 899 RESEARCH cult to measure accurately within a case-con- cant associations need to be interpret- cult for a study nding consumption cantly nal esti- infec- dence around our estimates. cult without standardization of methods; c risk factors. 1. Hall G, Kirk MD, Becker N, Gregory JE, Unicomb L, Millard G, et al. Estimating foodborne gastroenteritis, Australia. Emerg Infect Dis. 2005;11:1257–64. 2. Miller M, Roche P, Yohannes K, Spencer J, Bartlett M, Brotherton J, et al. Australia’s noti able diseases status, 2003 annual report of able Diseases Surveillance System. Commun Dis 3. Hall G, Raupach J, Yohannes K. An estimate of under-reporting of able diseases: (STEC). NCEPH working paper no. 52. Canberra (Australia): Australian National University; 2006. p. 4. Eberhart-Phillips J, Walker N, Garrett N, Bell D, Sinclair D, Rainger W, et al. Campylobacteriosis in New Zealand: results of a case-con-trol study. J Epidemiol Community Health. 1997;51:686–91. 5. Neimann J, Engberg J, Molbak K, Wegener HC. A case-control 6. Kapperud G, Espeland G, Wahl E, Walde A, Herikstad H, Gustavs- infection: a prospective case-control study in Nor-way. Am J Epidemiol. 2003;158:234–42. 7. Stafford RJ, Schluter P, Kirk M, Wilson A, Unicomb L, Ashbolt R, et al. A multi-centre prospective case-control study of campylobacter infection in persons aged 5 years and older in Australia. Epidemiol 8. Studahl A, Andersson Y. Risk factors for indigenous campy-lobacter infection: a Swedish case-control study. Epidemiol Infect. 9. Friedman CR, Hoekstra RM, Samuel M, Marcus R, Bender J, Shifer- infection in the 10. Rockhill B, Newman B, Weinberg C. Use and misuse of population attributable fractions. Am J Public Health. 1998;88:15–9.11. Australian Government Department of Health and Ageing. National able Diseases Surveillance System [cited 2005 May 20]. Avail-able from http://www9.health.gov.au/cda/Source/CDA-index.cfm12. Evans MR, Ribeiro CD, Salmon RL. Hazards of healthy living: infection. Emerg Infect Dis. 2003;9:1219–25.900 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 14, No. 6, June 2008 Infection, Australia 13. Wingstrand A, Neimann J, Engberg J, Nielsen EM, Gerner-Smidt P, Wegener HC, et al. Fresh chicken as main risk factor for campy-lobacteriosis, Denmark. Emerg Infect Dis. 2006;12:280–5.14. Voetsch AC, Van Gilder TJ, Angulo FJ, Farley MM, Shallow S, Mar-15. Wheeler JG, Sethi D, Cowden JM, Wall PG, Rodrigues LC, Tomp-in the community, presenting to general practice, and reported to national surveillance. The Infectious Intestinal Disease Study Ex-16. Roels TH, Wickus B, Bostrom HH, Kazmierczak JJ, Nicholson MA, Kurzynski TA, et al. A foodborne outbreak of 17. Gent RN, Telford DR, Syed Q. An outbreak of campylobacter food 18. Olsen SJ, Hansen GR, Bartlett L, Fitzgerald C, Sonder A, Manjrekar R, et al. An outbreak of infections associated eld gel electro-19. Frost JA, Gillespie IA, O’Brien SJ. Public health implications of campylobacter outbreaks in England and Wales, 1995–9: epide-2002;128:111–8. 20. Kirk M, Waddell R, Dalton C, Creaser A, Rose N. A prolonged out- infection at a training facility. Commun Dis 21. Harris NV, Weiss NS, Nolan CM. The role of poultry and meats enteritis. Am J Public Health. 1986;76:407–11.22. Kapperud G, Skjerve E, Bean NH, Ostroff SM, Lassen J. Risk fac- infections: results of a case-control study in southeastern Norway. J Clin Microbiol. 1992;30:3117–21.23. Rodrigues LC, Cowden JM, Wheeler JG, Sethi D, Wall PG, Cum-berland P, et al. The study of infectious intestinal disease in England: 24. Tenkate TD, Stafford RJ. Risk factors for campylobacter infection in infants and young children: a matched case-control study. Epidemiol 25. Benichou J. A review of adjusted estimators of attributable risk. Stat 26. Whittemore AS. Estimating attributable risk from case-control stud-ies. Am J Epidemiol. 1983;117:76–85.27. Coughlin SS, Benichou J, Weed DL. Attributable risk estimation in case-control studies. Epidemiol Rev. 1994;16:51–64.Address for correspondence: Russell J. Stafford, OzFoodNet (Queensland), Brisbane, Queensland 4001, Australia; email: russell_stafford@health.qld.gov.au Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 14, No. 6, June 2008 901 past Issues