"Sarah Finocchario-Kessler, at the University of Kansas, used data from one such drug trial to see what the effect of religious beliefs (and other psychological factors) was on medication taking.
She found that people who put themselves in God's hands really were less likely to take their medicine.
To be precise, people who used a passive religious deferral coping style (e.g. "I don’t try much of anything; simply expect God to take control") were less likely to take their medicine as often as they were supposed to. On the other hand, collaborative religious coping "I work together with God as partners" or self-directing religious coping (e.g., "I make decisions about what to do without God’s help" had no effect on whether people took their medicines.
The biggest effect was with those people who scored high on the "God as locus of health control" measure - that means people who agreed with statements like "Whether or not my HIV disease improves is up to God." "
Epiphenom.fieldofscience.com, Tom Rees, March 02, 2011