Guillain-Barré syndrome and influenza vaccines: A meta-analysis.

Cases of Guillain-Barré syndrome (GBS) have been occasionally associated with influenza vaccines; this possible risk, even if rare, is a matter of much concern. To investigate the strength of this association, a systematic review and a meta-analysis have been conducted; for the purpose, controlled observational studies addressing the risk of GBS associated with different influenza vaccines were sought. We finally selected 39 studies of interest published between 1981 and 2014 (seasonal influenza vaccines, 22; pandemic influenza vaccines, 16; both vaccines simultaneously administered, 1); funnel plot did not identify publication bias. At the association between any influenza vaccine - whether seasonal or pandemic - with GBS, the overall relative risk was 1.41 (95% CI, 1.20-1.66). Pandemic vaccines presented a higher risk (RR=1.84; 95% CI, 1.36-2.50) compared to seasonal vaccines (RR=1.22; 95% CI, 1.01-1.48); the latter should be considered as marginally statistically significant. Pandemic adjuvanted vaccines were not found to be related to a higher risk compared to non-adjuvanted vaccines. The results of the present meta-analysis point to a small but statistically significant association between influenza vaccines, particularly the pandemic ones, and GBS, which is consistent with current explanations upon possible mechanisms for this condition to appear.

Hip fracture rates and bisphosphonate consumption in Spain. An ecologic study.

INTRODUCTION: Bisphosphonates are used worldwide to treat osteoporosis and, thus, to prevent fractures. Though they have been proven in clinical trials to avoid some fractures, their effectiveness in reducing hip fractures is unclear. The aim of the present study was to explore the relationship between bisphosphonate use and hip fracture trends in Spain. METHODS: For this purpose, an ecologic study spanning 2002 to 2008 was conducted in Spain. Consumption data were obtained from the Spanish Ministry of Health and Social Policy. The number of hip fractures was obtained from hospital discharges; annual hip fracture rates were determined and standardized using the Spanish 2002 population census. A linear regression was performed between fracture rate and use of bisphosphonates; R(2) and Pearson correlation coefficient were calculated. RESULTS: From 2002 to 2008, dispensed prescriptions of bisphosphonates in Spain increased from 3.28 to 17.66 DDD/1,000 inhabitants per day. In the same period, the crude hip fracture rate increased from 2.85 to 3.02 cases per 1,000 inhabitants older than 50 years; however, when age standardized rates were estimated, the rate declined from 2.85 to 2.79. Analyzed by sex, the standardized rate for men slightly increased from 1.45 to 1.48, while for women the rate significantly dropped from 4.00 to 3.91. CONCLUSION: A small effect of bisphosphonates on hip fracture rates can not be ruled out; however, other factors might partially explain this decline. Assuming this medication was the only cause for hip fracture rate reduction, the elevated medication cost to avoid a single hip fracture makes it necessary to explore less expensive interventions.