Sex-specific risks for pediatric onset among patients with Crohn's disease

Increases in the incidence of pediatric Crohn's disease might reflect increases in incidence for onset at all ages or diagnostic improvement. Alternatively, there might be etiologic differences between adult and pediatric-onset disease with different risks for pediatric disease. Differences in sex ratio between adult and pediatric disease suggest etiologic differences might exist and also suggest differences in sex-specific susceptibility during childhood. This study seeks to identify whether factors previously associated with overall risk of Crohn's disease (number of siblings and maternal age) are associated with pediatric as opposed to adult onset among patients with Crohn's disease and whether these associations vary by sex.

A nested case-control study of patients with Crohn's disease was designed to compare pediatric with adult-onset disease. The participants were all patients with Crohn's disease in the Swedish Inpatient Register born between 1960 and 1998; 46.6% of the 4826 patients were male.

A notable association between mother's age at pregnancy and pediatric Crohn's disease was observed in female but not male patients. Compared with those whose mothers were younger than 21 years, female patients with older mothers, coded into ordered 5-year age categories, were at a higher risk of pediatric disease with adjusted odds ratios (95% confidence intervals) of 1.42 (0.85-2.37), 2.08 (1.19-3.66), 3.50 (1.83-6.69), 3.02 (1.35-6.75), and 12.64 (3.63-43.98). No statistically significant independent associations were observed for father's age or number of siblings.

Females might be more susceptible or more often exposed to factors associated with older maternal age at pregnancy that increase their risk of pediatric-onset Crohn's disease.