Assessing harmful effects in systematic reviews.
BACKGROUND
Balanced decisions about health care interventions require reliable evidence on harms as well as benefits. Most systematic reviews focus on efficacy and randomised trials, for which the methodology is well established. Methods to systematically review harmful effects are less well developed and there are few sources of guidance for researchers. We present our own recent experience of conducting systematic reviews of harmful effects and make suggestions for future practice and further research.


METHODS
We described and compared the methods used in three systematic reviews. Our evaluation focused on the review question, study designs and quality assessment.


RESULTS
One review question focused on providing information on specific harmful effects to furnish an economic model, the other two addressed much broader questions. All three reviews included randomised and observational data, although each defined the inclusion criteria differently. Standard methods were used to assess study quality. Various practical problems were encountered in applying the study design inclusion criteria and assessing quality, mainly because of poor study design, inadequate reporting and the limitations of existing tools. All three reviews generated a large volume of work that did not yield much useful information for health care decision makers. The key areas for improvement we identified were focusing the review question and developing methods for quality assessment of studies of harmful effects.


CONCLUSIONS
Systematic reviews of harmful effects are more likely to yield information pertinent to clinical decision-making if they address a focused question. This will enable clear decisions to be made about the type of research to include in the review. The methodology for assessing the quality of harmful effects data in systematic reviews requires further development.
McIntosh
Heather M
HM
Centre for Reviews and Dissemination, University of York, UK. hm14@york.ac.uk
Woolacott
Nerys F
NF
Bagnall
Anne-Marie
AM
D000927:Anticonvulsants / Q000009:adverse effects* / Q000627:therapeutic use; D014150:Antipsychotic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D016642:Bupropion / Q000008:administration & dosage / Q000009:adverse effects*; D003692:Delayed-Action Preparations; D006801:Humans; D015201:Meta-Analysis as Topic; D009538:Nicotine / Q000009:adverse effects* / Q000627:therapeutic use; D019370:Observation; D011786:Quality Control; D016032:Randomized Controlled Trials as Topic; D015203:Reproducibility of Results; D012107:Research Design; D012559:Schizophrenia / Q000188:drug therapy*; D016540:Smoking Cessation / Q000191:economics / Q000379:methods*; D016896:Treatment Outcome
D000927:Anticonvulsants; D014150:Antipsychotic Agents; D003692:Delayed-Action Preparations; D016642:Bupropion; D009538:Nicotine