Browsing by Author "Vargas C."

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    A strategy to impute age at onset of a particular condition from external sources
    (SAGE Publications Ltd, 2021) Alvares D.; Paredes F.; Vargas C.; Ferreccio C.; Paredes F.; Ferreccio C.; Vargas C.
    © The Author(s) 2021.A key hypothesis in epidemiological studies is that time to disease exposure provides relevant information to be considered in statistical models. However, the initiation time of a particular condition is usually unknown. Therefore, we developed a multiple imputation methodology for the age at onset of a particular condition, which is supported by incidence data from different sources of information. We introduced and illustrated such a methodology using simulated data in order to examine the performance of our proposal. Then, we analyzed the association of gallstones and fatty liver disease in the Maule Cohort, a Chilean study of chronic diseases, using participants’ risk factors and six sources of information for the imputation of the age-occurrence of gallstones. Simulated studies showed that an increase in the proportion of imputed data does not affect the quality of the estimated coefficients associated with fully observed variables, while the imputed variable slowly reduces its effect. For the Chilean study, the categorized exposure time to gallstones is a significant variable, in which participants who had short and long exposure have, respectively, 26.2% and 29.1% higher chance of getting a fatty liver disease than non-exposed ones. In conclusion, our multiple imputation approach proved to be quite robust both in the linear/logistic regression simulation studies and in the real application, showing the great potential of this methodology.
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    Medication review with follow-up for cardiovascular outcomes: A trial based cost-utility analysis
    (Academic Press, 2021) Ahumada-Canale A.; Martinez-Mardones F.; Garcia-Cardenas V.; Ahumada-Canale A.; Vargas C.; Balmaceda C.; Plaza-Plaza J.C.; Benrimoj S.
    © 2021 Future Medicine Ltd.. All rights reserved.Aim: To assess the trial-based cost-effectiveness of medication review with follow-up compared with usual care in primary care. Materials methods: A cluster randomized controlled trial included patients if they were independent older adults, receiving five or more prescriptions, with moderate or high cardiovascular risk. Costs were estimated from the public healthcare sector perspective, and health benefits were measured as quality-Adjusted life years. Both of which were used to calculate the incremental cost-effectiveness ratio. Results: Twelve centers completed the study, six (146 patients) in the intervention group and six (145 patients) in the control group. The base-case analysis showed an incremental cost-effectiveness ratio of US (2019) 434.4/quality-Adjusted life year (95% CI 64.20-996.03). Conclusion: The intervention was cost-effective in the public primary care setting.