Email updates

Keep up to date with the latest news and content from BMC Medical Research Methodology and BioMed Central.

Open Access Research article

On reporting results from randomized controlled trials with recurrent events

Lisa Kuramoto*, Boris G Sobolev and Meghan G Donaldson

BMC Medical Research Methodology 2008, 8:35  doi:10.1186/1471-2288-8-35

PubMed Commons is an experimental system of commenting on PubMed abstracts, introduced in October 2013. Comments are displayed on the abstract page, but during the initial closed pilot, only registered users can read or post comments. Any researcher who is listed as an author of an article indexed by PubMed is entitled to participate in the pilot. If you would like to participate and need an invitation, please email, giving the PubMed ID of an article on which you are an author. For more information, see the PubMed Commons FAQ.

Recurrent event time analysis

Andreas Wienke   (2009-09-23 09:38)  University Halle-Wittenberg email

Dear Sir,

Kuramoto et al. (2008) present a very interesting overview about models for the analysis of recurrent event time data. I would like to congratulate Kuramoto and colleagues to their nice and stimulating paper. However, I have one important comment on the article. Kuramoto et al. classify five approaches as appropriate models for the analysis of recurrent event times: the mean cumulative function, the Gamma-Poisson model, the independent-increment (Anderson-Gill) model, the conditional and the marginal model.

As the authors correctly state in their article the Gamma-Poisson model is in fact a frailty model with gamma distributed frailty and exponential baseline hazard function. This is a rather restricted model, assuming a constant recurrent event rate over time. It remains unclear why the authors restrict to this model in their paper instead of considering general frailty models (Duchateau and Janssen, 2008). In this class of models similar to the Cox proportional hazards model no parametric assumption about the baseline hazard function is necessary. Furthermore, additional to the gamma other frailty distributions can be used. These models are well designed for the analysis of recurrent event time data (Duchateau et al. 2003), including total follow-up time as well as gap time model variants. Software for frailty models is freely available in form of SAS macro's and R routines.

Based on this fact I strongly recommend avoiding the restriction to the Gamma-Poisson model and suggest to consider frailty models as an appropriate tool for analysing recurrent event times.

Sincerely yours

Andreas Wienke


Duchateau, L., Janssen, P., Kezic, I., Fortpied, C. (2003) Evolution of recurrent asthma event rate over time in frailty models. Applied Statistics 52, 355-363

Duchateau, L., Janssen, P. (2008) The Frailty Model. Springer, New York

Kuramoto, L., Sobolev, B.G., Donaldson, M.G. (2008) On reporting results from randomized controlled trials with recurrent events. BMC Medical Research Methodology 8, 35

Competing interests



Post a comment