RESULTS	The difference in compliance rates ( 16.4 % ) between the 2 groups was statistically significant ( Chi ( 2 ) = 6.69 , p < 0.001 ) with a relative risk of 1.29 ( 95 % confidence interval 1.18-1 .40 ) , and the results remained significant after a `` worst case '' sensitivity analysis involving 4 control group cases lost to follow-up .\