Example: Lost to Follow-up - HCV and HIV

Lead Author(s): Jeff Martin, MD

Many times lost to follow-up data is not presented.

First Example from a Study with HIV/HCV Co-infected Individuals - Greub

Greub's 2000 Study:

Second Example from a Study with HIV/HCV Co-infected Individuals - Sulkowski

Sulkowski's 2002 Study:

Analysis of Studies

These are two studies in prestigious journals, who were allowed to publish their results without any data on loss to follow-up or its potential effect on their results. Something they would not have been allowed to do if these were experimental cohorts (i.e., clinical trials).

They are both treatment clinic-based cohorts, which means they counted a patient as in the cohort after two visits to the clinic (a little like a run-in design in a clinical trial where you test whether someone is going to be compliant before enrolling him or her). It also means that their follow-up was driven by return visits to the clinic.

Since they got contrary results with almost identical methodology, one would like to know whether differing follow-up biases had anything to do with the differing results. There is no way to tell from what they published.


Greub, G., Ledergerber, B., Battegay, M., Grob, P., Perrin, L., Furrer, H., et al. (2000). Clinical progression, survival, and immune recovery during antiretroviral therapy in patients with HIV-1 and hepatitis C virus coinfection: the Swiss HIV Cohort Study. Lancet, 356(9244), 1800-1805.

Sulkowski, M. S., Moore, R. D., Mehta, S. H., Chaisson, R. E., & Thomas, D. L. (2002). Hepatitis C and progression of HIV disease. Jama, 288(2), 199-206.