[R-sig-Epi] Paired by exposure

[BXC (Bendix Carstensen)]

This is not what we would call a paired design, because you are not pairing the OUTCOME, but the EXPOSURE.

You are merely taking a sample of the exposed and a sample of the non-exposed, and making sure that they have the same distribution of age at entry / date of birth / date of entry --- which one(s)?

Estimating mortality (morbidity?) in each of the two groups and the rate-ratio between them is just a straight-forward cohort analysis, either using a Poisson-model or a Cox-model. You will have to consider what time-scale you use for the description, though. And you must be sure that you are not using any of the follow-up information in your selection of persons to enter the study.

Best regards,
Bendix Carstensen
______________________________________________

Bendix Carstensen
Senior Statistician
Steno Diabetes Center
Niels Steensens Vej 2-4
DK-2820 Gentofte
Denmark
+45 44 43 87 38 (direct)
+45 30 75 87 38 (mobile)
bxc at steno.dk   http://www.biostat.ku.dk/~bxc

> -----Original Message-----
> From: r-sig-epi-bounces at stat.math.ethz.ch
> [mailto:r-sig-epi-bounces at stat.math.ethz.ch] On Behalf Of
> Pedro Emmanuel Alvarenga Americano do Brasil
> Sent: 5. september 2008 16:01
> To: r-sig-epi at stat.math.ethz.ch
> Subject: Re: [R-sig-Epi] Paired by exposure
>
> >
> > Dear R friens,
> >
> > I will start a project this month wiht a partner which is
> disigned as
> > a quasi-experiment. We are interrested in estimate risk
> raios and rate
> > ratios, possibly survival analysis. Everything is registered at
> > medical charts form the last 22 yaers. So everythig is
> retorspective.
> > However, due to a efficiency matters, we dicided to select the
> > non-exposed matching to the exposed. So for every paciente
> that took
> > this paticular medicine, we intend ot match one that did
> not take, and
> > start the follow-up in the same year and has no more than
> 10 years older than the exposed.
> >
> > I have looked up for more recent things than those I have
> in Klienbaum
> > and Rothman but it seems that the very good old friend
> ajusted MH for
> > the pair is the recomended.
> >
> > Does anyone have other sugestions? Does any knows a package or
> > functions to run paired risk or rate analysis?
> >
>
>    Best regards
>
> >
> > --
> > Abraço forte e que a força esteja com você, Pedro Emmanuel
> >
>
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