title: A transitional model of barrier methods compliance with unbalanced loss to follow-up.
abstract: Differential loss to follow-up can substantially influence the evaluation of treatment effects on a dichotomous outcome of interest in longitudinal trials. The use of transitional models incorporating loss to follow-up as an additional category of response and the nature of the correlated responses can provide a comprehensive view of a trial with unbalanced loss to follow-up. Under the Markov assumption, transitional models estimate the probability of changing from one outcome to another outcome between follow-up visits. Patterns of the response variable can be described by the estimated transition probabilities. The effects of intervention and covariates on the outcome of interest can also be estimated using a conditional likelihood function or a multinomial logit regression. Data from a randomized barrier method study designed to compare the proportion of participants using barrier methods consistently in two counselling groups are used to illustrate the proposed model.
authors.affiliation: Family Health International, P.O. Box 13950, Research Triangle Park, North Carolina 27709, USA.
authors.forename: P L
authors.initials: PL
authors.lastname: Chen
authors.forename: E
authors.initials: E
authors.lastname: Wong
authors.forename: R
authors.initials: R
authors.lastname: Dominik
authors.forename: M J
authors.initials: MJ
authors.lastname: Steiner
mesh_terms: D000293:Adolescent; D000328:Adult; D017280:Condoms; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016013:Likelihood Functions; D008137:Longitudinal Studies; D008297:Male; D015233:Models, Statistical; D016017:Odds Ratio; D010349:Patient Compliance; D011446:Prospective Studies; D012044:Regression Analysis; D012307:Risk Factors; D012747:Sexual Partners; D012749:Sexually Transmitted Diseases / Q000517:prevention & control; D013089:Spermatocidal Agents; D013997:Time Factors
chemical_list: D013089:Spermatocidal Agents