Birth Order and Risk of Non-Hodgkin Lymphoma-True Association or Bias?

作者：Grulich Andrew E^*; Vajdic Claire M; Falster Michael O; Kane Eleanor; Smedby Karin Ekstrom; Bracci Paige M; de Sanjose Silvia; Becker Nikolaus; Turner Jenny; Martinez Maza Otoniel; Melbye Mads; Engels Eric A; Vineis Paolo; Costantini Adele Seniori; Holly Elizabeth A; Spinelli John J; La Vecchia Carlo; Zheng Tongzhang; Chiu Brian C H; Franceschi Silvia; Cocco Pierluigi; Maynadie Marc; Foretova Lenka; Staines Anthony; Brennan Paul; Davis Scott

来源：American Journal of Epidemiology, 2010, 172(6): 621-630.

DOI：10.1093/aje/kwq167

• birth order
• case-control studies
• lymphoma
• non-Hodgkin
• selection bias
• social class

There is inconsistent evidence that increasing birth order may be associated with risk of non-Hodgkin lymphoma (NHL). The authors examined the association between birth order and related variables and NHL risk in a pooled analysis (1983-2005) of 13,535 cases and 16,427 controls from 18 case-control studies within the International Lymphoma Epidemiology Consortium (InterLymph). Overall, the authors found no significant association between increasing birth order and risk of NHL (P-trend = 0.082) and significant heterogeneity. However, a significant association was present for a number of B- and T-cell NHL subtypes. There was considerable variation in the study-specific risks which was partly explained by study design and participant characteristics. In particular, a significant positive association was present in population-based studies, which had lower response rates in cases and controls, but not in hospital-based studies. A significant positive association was present in higher-socioeconomic-status (SES) participants only. Results were very similar for the related variable of sibship size. The known correlation of high birth order with low SES suggests that selection bias related to SES may be responsible for the association between birth order and NHL.

• 出版日期2010-9-15