This is an example where a random effect meta-analysis model would not appear to be a suitable model for this data and a more measured analysis would consider both study sample size and patient baseline risk as important covariates which need to be taken into consideration [ 36].
The genotyping success rate for rs1569198 was 95.7% and for rs3962158 was 97.3%, with 100% concordance observed in duplicate samples run both within the replication study samples, and across the replication and discovery study samples.
Sources for divergent findings may be conceived in terms of both the heterogeneity of the study samples and differences in the measurement of the procedures.
Quality control (QC) samples for livers and sera were prepared from pooled partial study samples and injected every five study samples to monitor intra-batch precision.
In addition, multiple confounders assessed in our statistical models have plausible association with both depressed mood and LBW in both our study sample and the overall population.
Both the study sample and the recruitment process may limit the external validity of the study.
Several limitations of this study should be addressed related to both the study sample and the explorative nature of the study.
Age and gender distribution of both the study sample and the non-participant sample were similar with mean age being respectively 61.10 years (SD = 11.73) and 62.93 years (SD = 12.66), t-value = 1.88, p-value of 0.06 and gender distribution, 38.10 and 45.45 % males, χ = 3.3547, p-value of 0.07.
Identifiers common to both the study sample and the VAED were the national health insurance (Medicare) card number and suffix (i.e., a given or middle name abbreviated to first 3 letters), date of birth, postcode, sex and country of birth.
In both studies, samples taken in Kenya and Tanzania were banked samples collected opportunistically during other research activities in the study areas.
