Data analysis
We carried out meta-analysis using STATA version 14.2 (StataCorp,
College Station, TX, USA) and based on the recommendation for the
meta-analysis of observational studies. We conducted meta-analysis only
among those studies that reported type 2 diabetes. Heterogeneity among
studies was assessed with the Cochran chi-square (χ2) and quantified
with the I2 and tau-square (τ2) and
the values have been mentioned in the text. Substantial heterogeneity
was anticipated when I 2 values were greater
than 75%. The pooled proportion was estimated using the inverse
variance method. Confidence Interval (CI) was estimated at 95% for each
proportion. Random effects model was used for the overall pooled
estimate meta-analysis. We did not conduct meta-analyses for factors
affecting non-adherence, as ORs were reported in less than five
dimensions of adherence defined by the WHO, including conditions-related
factors, health care system-related factors, social and economic
factors, therapy-related factors and patient-related factors14.