A systematic review of injury/illness prevention and loss control ...

High quality studiesNine studies were determined to be of high quality (Amick et al. 2003; Bohret al. 2000; Faucett et al. 2002; Gerr et al. 2005; Hlobil et al. 2005; Jensen etal. 2005; Jensen et al. 2006; Rempel et al. 2006; Martin et al. 2003). The highquality studies had quality scores ranging between 31 and 34 out of a possible36 (86-94%). Despite being categorized as high quality, only five of thestudies reported drop-out rates. Only six reported their recruitment rate andhad a recruitment rate > 40%.Medium quality studiesWe classified 44 of the studies as medium quality. The medium qualitystudies often differed from the high quality studies in randomization (only 16described randomization), not describing the loss to follow-up (14 describedloss to follow-up) or making adjustment for pre-intervention differencesbetween groups. Similar to the high quality studies, the medium qualitystudies did not generally describe recruitment rate (16 of 44 did) or reportdrop-out differences between the groups. All but one study had anadequately stated research question, as did the high quality studies. Themedium quality studies did not score 100% on any of the individual qualitycriteria, compared with nine questions in the high quality studies that didscore 100%.Low quality studiesNineteen studies were rated as low quality. The low quality studies scoredabove 90% on only the research question criterion. They scored above 50%on only four of the 16 quality criteria (were time-based comparisons used;was a research question clearly stated; was the intervention process described;when were outcomes measured). Overall, the low quality studies did notprovide detailed information regarding factors that could affect the validity ofthe statistics presented in the studies (e.g. drop out rates, loss to follow-up,confounders/covariates).3.3 Data extraction resultsData was extracted from the 53 high and medium quality studies. Of thesestudies, only 46 completed direct statistical testing between the interventionand control groups; therefore, only 46 studies are discussed in data extractionand evidence synthesis. The 46 studies were categorized by interventioncategory. The categories were developed and agreed upon by the mainauthors of this review. Appendix K includes the intervention categories anddetailed descriptions of interventions in each study.Intervention categoriesTwenty different interventions were identified. Five of the studies evaluatedmore than one intervention:22 Institute for Work & Health