Power calculations for cluster randomized trials (CRTs) with right-truncated Poisson-distributed outcomes: a motivating example from a malaria vector control trial.
Int J Epidemiol
; 49(3): 954-962, 2020 06 01.
Article
in En
| MEDLINE
| ID: mdl-32011684
ABSTRACT
BACKGROUND:
Cluster randomized trials (CRTs) are increasingly used to study the efficacy of interventions targeted at the population level. Formulae exist to calculate sample sizes for CRTs, but they assume that the domain of the outcomes being considered covers the full range of values of the considered distribution. This assumption is frequently incorrect in epidemiological trials in which counts of infection episodes are right-truncated due to practical constraints on the number of times a person can be tested.METHODS:
Motivated by a malaria vector control trial with right-truncated Poisson-distributed outcomes, we investigated the effect of right-truncation on power using Monte Carlo simulations.RESULTS:
The results demonstrate that the adverse impact of right-truncation is directly proportional to the magnitude of the event rate, λ, with calculations of power being overestimated in instances where right-truncation was not accounted for. The severity of the adverse impact of right-truncation on power was more pronounced when the number of clusters was ≤30 but decreased the further the right-truncation point was from zero.CONCLUSIONS:
Potential right-truncation should always be accounted for in the calculation of sample size requirements at the study design stage.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Randomized Controlled Trials as Topic
Type of study:
Clinical_trials
Limits:
Humans
Language:
En
Journal:
Int J Epidemiol
Year:
2020
Document type:
Article
Affiliation country:
United kingdom
Publication country:
ENGLAND
/
ESCOCIA
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GB
/
GREAT BRITAIN
/
INGLATERRA
/
REINO UNIDO
/
SCOTLAND
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UK
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UNITED KINGDOM