Objective — To determine whether safety warnings issued by health regulatory agencies regarding desmopressin treatment influenced treatment rates among children. 

Patient population and methods—The authors conducted a time-series analysis using health administrative data from Ontario, Canada, between January 1, 2003 and March 31, 2010. The authors examined desmopressin prescribing rates among children (<13 years) and investigated the impact of a United States Food and Drug Administration warning (December 2007) and a subsequent Health Canada warning (July 2008) on these rates. A secondary analysis stratified rates according to route of administration.

Results — On average, quarterly desmopressin treatment rates were 29.8% lower following the two warnings (4.7 per 1,000 population) compared with the period prior to warnings being issued (6.7 per 1,000 population).

Structural break analyses identified a significant decrease in overall desmopressin prescribing rates in Q3 2008, with the 95% confidence interval (CI) spanning both safety warnings (Q4 2007 to Q1 2009). A secondary analysis of prescribing rates for oral formulations found consistent results (structural break Q4 2008, 95% CI Q2 2007 to Q2 2009). The average quarterly prescribing rate of intranasal formulations declined by 73.1% following the warnings compared with the period preceding the warnings.

Conclusion — Safety warnings issued by regulatory agencies dramatically influenced desmopressin use among Ontario's children.