Subgroup analyses were further performed according to ethnicity, source of the controls, and NHL subtype.
Stratified analyses were conducted by ethnicity, source of control and disease type.
Subgroup analysis was conducted after stratifying by ethnicity (Asians, Caucasians, and mixed ethnicity), source of the controls (hospital-based and population-based), or the NHL subtypes (DLBCL and FL).
Then, we assessed the source of heterogeneity by ethnicity, source of controls, genotyping methods, publication year, and sample size (subjects > 500 in both cases and controls).
Meta-regression was employed to explore the potential sources of heterogeneity including publication date, ethnicity, source of controls, mean age of control and case group, and sex.
Upon stratifying the data by ethnicity, source of the controls, and NHL subtype, no association between the Asp312Asn polymorphism and NHL risk was detected.
For every study, publication date, country of origin, demographics, genotyping methodology, ethnicity, source and genotype frequency of study subjects were reviewed.
The subgroup analysis also failed to reveal any association between the examined polymorphisms and NHL risk according to ethnicity, source of the controls, or NHL subtype.
Moreover, based on the subgroup analyses, ethnicity, source of the controls, and NHL subtype had no effect on the association between the Lys751Gln polymorphism and NHL risk.
a. Demographic characteristics: Age, gender, ethnicity, source of referral, area of residence and smoking status, where ethnicity was used according to Census population classification data: African (black), white, Indian and coloured [ 13].
