L10: Simple time-varying exposures
Readings
- Lu H, Cole SR, Westreich D, Hudgens MG, Adimora AA, Althoff KN, Silverberg MJ, Buchacz K, Li J, Edwards JK, Rebeiro PF. Clinical Effectiveness of Integrase Strand Transfer Inhibitor–Based Antiretroviral Regimens Among Adults With Human Immunodeficiency Virus: A Collaboration of Cohort Studies in the United States and Canada. Clinical Infectious Diseases. 2020 Aug 11.
Notes
We are often interested in estimating the effects of treatments or interventions that are maintained over time, but exposures to these treatments and interventions often vary over time for participants in our datasets. Reasons may include
- treatment changes or discontinuation
- nonadherence
- loss to follow-up
- mobility and migration
among others.
This week, we will focus on a simple scenario in which we want to compare risk of death under continuous treatment and under no treatment, but some people in the treatment arm discontinue treatment. In the exercise, we will compare risk under 2 treatments, where people in both arms discontinue treatment.
Videos
Recordings of lectures are available on the EPID 722 Sakai site.
Exercise
Exercise 10 may be found on the course Teams site.
Optional readings
In the reading and during lecture, we discussed using IPW to estimate “per protocol” effects in the presence of a simple time-varying exposure. The reading below illustrates use of g computation to achieve the same goals.
Naimi AI, Perkins NJ, Sjaarda LA, Mumford SL, Platt RW, Silver RM, Schisterman EF. The Effect of Preconception-Initiated Low-Dose Aspirin on Human Chorionic Gonadotropin–Detected Pregnancy, Pregnancy Loss, and Live Birth: Per Protocol Analysis of a Randomized Trial. Annals of Internal Medicine. 2021 Jan 26.
The reading also introduced the idea of emulating a randomized trial using observational data. For more on this idea, see
Hernán MA, Robins JM. Using big data to emulate a target trial when a randomized trial is not available. American journal of epidemiology. 2016 Apr 15;183(8):758-64.
Questions
Please use the form below to submit your questions about this week’s reading.