TY - JOUR
T1 - Infections presenting for clinical care in early life and later risk of hay fever in two UK birth cohorts
AU - Bremner, S. A.
AU - Carey, I. M.
AU - DeWilde, S.
AU - Richards, N.
AU - Maier, W. C.
AU - Hilton, S. R.
AU - Strachan, D. P.
AU - Cook, D. G.
PY - 2008/3
Y1 - 2008/3
N2 - Background: The 'hygiene hypothesis' proposes that infections in infancy protect against hay fever (HF). We investigated infections during infancy in relation to HF, including rarer ones not previously researched in this context, while examining the role of potential confounding variables. Methods: From birth cohorts derived within the General Practice Research Database (GPRD) and Doctors Independent Network (DIN) database of computerized patient records from UK general practice, we selected 3549 case-control pairs, matched for practice, age, sex and control follow-up to case diagnosis. Conditional logistic regressions were fitted for each of 30 infections; behavioural problems (BP) acted as a control condition unrelated to HF. Odds ratios (OR), adjusted for consultation frequency were pooled across the databases using fixed effect models. We also adjusted for sibship size in GPRD and a socioeconomic marker in DIN. Results: Upper respiratory tract infections, diarrhoea and vomiting and acute otitis media in infancy were each related with a moderately increased risk of HF in both databases, as were BP. These associations were lost on adjustment for consultation frequency. Only bronchiolitis was significantly associated with a reduced pooled risk of HF after adjustment for consultations (OR = 0.8). Adjustment for sibship size in GPRD and a socioeconomic marker in DIN had little impact on the OR. Conclusions: Of 30 infectious illnesses investigated, none had strong or consistent associations with HF after adjustment for consultation frequency. Except for bronchiolitis, possibly a chance finding, none of the clinically apparent infections considered appear to have an important role in allergy prevention.
AB - Background: The 'hygiene hypothesis' proposes that infections in infancy protect against hay fever (HF). We investigated infections during infancy in relation to HF, including rarer ones not previously researched in this context, while examining the role of potential confounding variables. Methods: From birth cohorts derived within the General Practice Research Database (GPRD) and Doctors Independent Network (DIN) database of computerized patient records from UK general practice, we selected 3549 case-control pairs, matched for practice, age, sex and control follow-up to case diagnosis. Conditional logistic regressions were fitted for each of 30 infections; behavioural problems (BP) acted as a control condition unrelated to HF. Odds ratios (OR), adjusted for consultation frequency were pooled across the databases using fixed effect models. We also adjusted for sibship size in GPRD and a socioeconomic marker in DIN. Results: Upper respiratory tract infections, diarrhoea and vomiting and acute otitis media in infancy were each related with a moderately increased risk of HF in both databases, as were BP. These associations were lost on adjustment for consultation frequency. Only bronchiolitis was significantly associated with a reduced pooled risk of HF after adjustment for consultations (OR = 0.8). Adjustment for sibship size in GPRD and a socioeconomic marker in DIN had little impact on the OR. Conclusions: Of 30 infectious illnesses investigated, none had strong or consistent associations with HF after adjustment for consultation frequency. Except for bronchiolitis, possibly a chance finding, none of the clinically apparent infections considered appear to have an important role in allergy prevention.
KW - General Practice databases
KW - Hay fever
KW - Infections
KW - Nested case-control study
UR - http://www.scopus.com/inward/record.url?scp=38949212475&partnerID=8YFLogxK
U2 - 10.1111/j.1398-9995.2007.01599.x
DO - 10.1111/j.1398-9995.2007.01599.x
M3 - Article
C2 - 18269673
AN - SCOPUS:38949212475
SN - 0105-4538
VL - 63
SP - 274
EP - 283
JO - Allergy: European Journal of Allergy and Clinical Immunology
JF - Allergy: European Journal of Allergy and Clinical Immunology
IS - 3
ER -