[Impact of mass media on the use of health services. A systematic review of the literature].
BACKGROUND
Mass media may influence the use of health services either through campaigns promoting the use of specific procedures or through the coverage of health related issues outside the context of a planned intervention. To assess their effect on the utilization of health services a systematic overview of primary research was undertaken.


METHODS
Experimental and quasi experimental studies meeting pre defined entry criteria and providing information on the impact of mass media on objective measures on health services utilization were searched through Medline, Embase, Psychlit, Eric, as well as handsearching key journals. Data on the detail and content of interventions were abstracted and raw data describing health services utilization obtained. Effect sizes were calculated for each study and then pooled across studies on the same topic using a random effects model.


RESULTS
Out of 69 papers providing information on the impact of mass media on aspects of health services utilization, 17 interrupted time series met our quality criteria. Fourteen evaluated the impact of formal mass media campaigns, 3 of media coverage of health related issues. The overall methodological quality was rather variable, with 6 studies not performing any statistical analysis, and 7 using inadequate statistical tests (i.e. not taking into account the effect of time trend). All the studies but the concluded positively on the effect of mass media. These positive findings were confirmed by our re-analysis in 7, while in the remaining the effect of mass media was not statistically significant. The direction of effect was consistent across individual studies and the pooled effect sizes revealed an effect upon the utilization of health services that could not be explained by chance alone, ranging from -1.96 (95% CI: -1.19, -2.73) for campaigns promoting immunization programs, to -1.12 (95% CI: -0.49, -2.46) for those concerning cancer screening.


CONCLUSIONS
Despite the overall limited quality of primary research, this review supports the view that these channels of communication may have an important role in influencing the use of health care interventions. Mass media should be considered as one of the tools that may encourage the use of effective services and discourage those of unproved effectiveness.
Grilli
R
R
Unita Valutazione Interventi Sanitari Lab. Ricerca Servizi Sanitari Istituto M. Negri, Milano (I).
Freemantle
N
N
Minozzi
S
S
Domenighetti
G
G
Finer
D
D
D003627:Data Interpretation, Statistical; D006266:Health Education; D006293:Health Promotion; D006296:Health Services / Q000706:statistics & numerical data*; D006801:Humans; D008402:Mass Media