The National Toxicology Program (NTP) has been taking a lead role in developing a systematic review process for literature based evaluations in environmental health sciences. Systematic review methods include predefined procedures to identify, select, critically assess, and synthesize evidence from scientific studies to reach conclusions. These techniques increase the transparency and objectivity in the course of answering specific research questions. The NTP Office of Health Assessment and Translation (OHAT) has developed a seven-step systematic review process that is nicely described in a new handbook that went online in January.
The “Handbook for Conducting a Literature-Based Health Assessment Using OHAT Approach for Systematic Review and Evidence Integration” provides standard operating procedures for the implementation of systematic review in OHAT evaluations. The handbook was developed based on lessons learned from developing two case studies, public comments, and from discussions with experts in toxicology, public health, and systematic review methods.
Along with the handbook, OHAT has released an updated approach or tool for assessing the risk of bias in a study’s findings. The OHAT risk-of-bias tool outlines procedures for evaluating risk of bias for both human and animal studies and is similar to methods used to critically assess clinical trials of new drugs.
Having and using an established systematic review process lets everyone see exactly how conclusions about potential human health hazards are reached. Also, NTP is hopeful that once the methodology becomes adopted more widely, the reproducibility of environmental health studies will be enhanced.