RT Journal
A1 Chan M
T1 ADverse events in patients receiving cholinesterase inhibitors due to dissimilar follow-up periods
JF Archives of Internal Medicine
JO Archives of Internal Medicine
YR 2009
FD October 12
VO 169
IS 18
SP 1718
OP 1725
DO 10.1001/archinternmed.2009.347
UL http://dx.doi.org/10.1001/archinternmed.2009.347
AB 
It is interesting to note that while the incidence of hospital visits for syncope are comparatively higher in the cholinesterase inhibitor cohort (2.2% vs 1.5% in controls, see Table 3 in Gill et al1), the incidences for all other adverse outcomes are actually almost identical between cholinesterase inhibitor and control groups (hospital visits for bradycardia, 0.5% vs 0.4%; pacemaker insertions, 0.3% vs 0.3%; and hospitalizations for hip fractures, 1.6% vs 1.6%). The significant difference noted in the event rates and subsequent hazard ratios are therefore mainly influenced by the shorter follow-up periods reported for the cholinesterase inhibitor group (hospitalization due to hip fractures, mean follow-up times were 252 days and 302 days for the cholinesterase inhibitor and control cohorts, respectively.) Unfortunately, there was no clarification for this disparity in the article text.