Seven years of workplace drug testing in Italy: a systematic review and meta-analysis

Background In Italy, Workplace Drug Testing (WDT) is compulsory by law for specific categories of workers since 2008, offering the opportunity to compare studies conducted within a single regulatory framework. Aims (i) To estimate the overall prevalence of WDT positivity (at screening survey) among Italian workers. (ii) To evaluate the percentage of true and false positives at confirmation analysis. Methods Systematic review and meta-analysis of the scientific literature on WDT in Italy from January 2008 to March 2015, according to the MOOSE Guidelines. A random effects model was utilised to calculate pooled prevalence. Potential sources of heterogeneity were explored using sensitivity test and subgroup analysis. Results The overall meta-analytical prevalence of positivity at WDT among Italian workers was 1.4% [95% confidence interval (CI) = 1.1–1.7%]. It was significantly lower among workers screened with an on-site test (1%; 95% CI = 0.5–1.5%), compared with a bench-top test (1.7%; 95% CI = 1.3–2.1%). Nine studies provided data on false positives at the screening test, with a combined prevalence estimate - calculated on positive cases - of 30% (95% CI = 16-44%). Conclusion In Italy, the number of true positives at first level workplace drug testing is low, while the frequency of false positives is relatively high. A revision of the Italian legislation on the subject seems advisable.