highly significantP < 0.001
Heterogeneity and publication bias There was considerable heterogeneity among the included studies, so that the result of Chi 2 test for heterogeneity was highly significant ( P < 0.001).
Heterogeneity and publication bias There was considerable heterogeneity among the included studies, so that the result of Chi 2 test for heterogeneity was highly significant ( P < 0.001).
The prevalence was higher in older age groups, in women, and in the northern regions of the country, with an increasing trend in recent years.