Impact on decisions to start or continue medicines of providing information to patients about possible benefits and/or harms: a systematic review and meta-analysis.

BACKGROUND The impact of providing information about medicines to patients on decisions about starting or continuing them is unknown. PURPOSE To estimate the impact on decisions to start or continue medicines, of providing information to patients about possible benefits and/or harms. DATA SOURCES Electronic searches from 1980 to October 2010; reference and citation searches of included studies. STUDY SELECTION Two investigators assessed studies' eligibility against inclusion criteria: randomized or pseudorandomized trials; participants older than 16 years and deciding for themselves; one group received information about possible benefits and/or harms of a potentially beneficial medicine, compared with another who did not; d) a measure of decision about starting or continuing a medicine. DATA EXTRACTION One investigator extracted all data, checked by a second. DATA SYNTHESIS Eight studies were included, covering a range of medicines. There was no consistent impact of interventions on decisions about whether to start or continue medicines (pooled odds ratio 1.08; 95% confidence interval [CI], 0.69-1.70; P = 0.74). Among those who received more information, knowledge was increased (pooled mean difference 8.47; 95% CI 2.17-14.77; P = 0.008), and decisional conflict was reduced (pooled mean difference -0.15; 95% CI -0.24 to -0.06; P = .001). LIMITATIONS A small number of studies across different clinical contexts, of uncertain heterogeneity, were included. CONCLUSIONS Providing information to patients about possible benefits and/or harms has no consistent effect on the number who decide to start or continue medicines, although it increases patients' knowledge and reduces their decisional conflict.