Table 2.

Examples of the four study designs

1. Safety needles & workshop on needle stick injuries [9] Intervention: technical device on safety needles & interactive workshop in health care workers. Outcome characteristics: frequent & shorter latency needle stick injuries. Evaluation design: cluster randomized controlled trial. Results: 66% reduction in needle stick injuries [odds ratio: 0.34; 95% confidence interval (CI): 0.13–0.91).

2. Regulation, market, & education on occupational asthma [10], [11] Interventions: national legislation, market forces, education, & regulatory activity. Outcome characteristics: frequent & longer latency occupational asthma. Evaluation design: controlled before & after study. Results: positive impact of legislation & changes in the supply chain (e.g., latex & glutaraldehyde) but less evidence of impact of education and regulatory activity (e.g., flour).

3. Regulation on occupational injuries [12] Intervention: regulation on safety measures in construction workers. Outcome characteristics: nonfrequent & shorter latency fatal & nonfatal injuries. Evaluation design: meta-analysis on interrupted time series in systematic review. Results: initial & sustained increase in fatal (effect size of 0.79; 95% CI: 0.00–1.58) & nonfatal injuries (effect size 0.23; 95% CI 0.03–0.43).

4. Screening program & regulation on solvent induced encephalopathy [13] Intervention: ban on indoor use of solvent-based paints & workers health surveillance in painters. Outcome characteristics: nonfrequent, longer latency chronic solvent-induced encephalopathy. Evaluation design: case series (yearly) on screening. Results: downwards trend year prevalence of newly diagnosed chronic solvent-induced encephalopathy from max 102 cases to 1 case.