Stroke incidence in Hong Kong after recall of contaminated generic valsartan

Abstract

Introduction: The Department of Health of Hong Kong notified doctors and issued a press release on 6 July 2018 about the recall of five products containing valsartan contaminated by N-itrosodimethylamine. Because sudden cessation of antihypertensive treatment can cause strokes, we studied the incidence of strokes to detect a possible increase following the recall. Methods: Stroke episodes occurring from 7 July to 10 October 2018 were identified from the Clinical Data Analysis and Report System of the Hong Kong Hospital Authority. The number of strokes on each day was ascertained. As there is seasonal variation in the incidence of stroke, we used the corresponding period in 2017 for comparison. The mean number of strokes per day was analysed using unpaired t test. Results: There were 5022 and 4717 stroke episodes in the respective time periods in 2017 and 2018. The daily incidence (mean ± standard deviation) was 52 ± 10 in 2017 and 52 ± 11 in 2018 (P>0.05). The mean difference (95% confidence interval) was 0.92 (-1.97 to 3.80). Conclusions: Our results show no statistically significant increase in the number of strokes in Hong Kong following the drug recall. The fear was that hypertensive patients might have stopped taking their medications out of confusion. Our figures show that the withdrawal and replacement of the generic valsartan products were well managed, and there is no evidence of any increase in strokes during this period.