Demographics and risk factors for otitis prone and healthy children in this study.

NTHi, nontypeable Haemophilus influenzae; PD, protein D. p<0.05 was considered statistically significant. aThe total number of AOM episodes was not recorded for 1 otitis-prone child but they fitted the inclusion criteria of at least 3 doctor-diagnosed episodes of AOM. bDay-care attendance was not recorded for 1 child. cViral PCR was not conducted on nasopharyngeal (NP) swabs from 3 cases and 1 control. dNP swab was not cultured for 1 control. eNo serum IgG data for 2 cases and 1 control.