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Comparison of two control groups for estimation of oral cholera vaccine effectiveness using a case-control study design.
- Source :
-
Vaccine [Vaccine] 2017 Oct 13; Vol. 35 (43), pp. 5819-5827. Date of Electronic Publication: 2017 Sep 12. - Publication Year :
- 2017
-
Abstract
- Background: Case-control studies to quantify oral cholera vaccine effectiveness (VE) often rely on neighbors without diarrhea as community controls. Test-negative controls can be easily recruited and may minimize bias due to differential health-seeking behavior and recall. We compared VE estimates derived from community and test-negative controls and conducted bias-indicator analyses to assess potential bias with community controls.<br />Methods: From October 2012 through November 2016, patients with acute watery diarrhea were recruited from cholera treatment centers in rural Haiti. Cholera cases had a positive stool culture. Non-cholera diarrhea cases (test-negative controls and non-cholera diarrhea cases for bias-indicator analyses) had a negative culture and rapid test. Up to four community controls were matched to diarrhea cases by age group, time, and neighborhood.<br />Results: Primary analyses included 181 cholera cases, 157 non-cholera diarrhea cases, 716 VE community controls and 625 bias-indicator community controls. VE for self-reported vaccination with two doses was consistent across the two control groups, with statistically significant VE estimates ranging from 72 to 74%. Sensitivity analyses revealed similar, though somewhat attenuated estimates for self-reported two dose VE. Bias-indicator estimates were consistently less than one, with VE estimates ranging from 19 to 43%, some of which were statistically significant.<br />Conclusions: OCV estimates from case-control analyses using community and test-negative controls were similar. While bias-indicator analyses suggested possible over-estimation of VE estimates using community controls, test-negative analyses suggested this bias, if present, was minimal. Test-negative controls can be a valid low-cost and time-efficient alternative to community controls for OCV effectiveness estimation and may be especially relevant in emergency situations.<br /> (Copyright © 2017. Published by Elsevier Ltd.)
Details
- Language :
- English
- ISSN :
- 1873-2518
- Volume :
- 35
- Issue :
- 43
- Database :
- MEDLINE
- Journal :
- Vaccine
- Publication Type :
- Academic Journal
- Accession number :
- 28916247
- Full Text :
- https://doi.org/10.1016/j.vaccine.2017.09.025