Hello epidata friends,

Im occasionally reading emails in the list about limitations in the related rec files. The last I remember was about double entry, which I did not read a proposition of solution. Here goes another problems that I could not solve yet.

Im working with a dataset entry with two purposes: 1) to estimate a trajectory of a particular liver enzyme over time while patients is under therapy and 2) estimate the risk of liver toxicity while in therapy. The tow objectives are time dependent.

In the first objective the possible result is a graph with a line conecting dots which represents the enzyme values in each time point.

The second is a cox model or a exponential survival model which the outcome is liver toxicity due to therapy. In this one, the medications may change over time.

Therefore I was imagining creating a main recfile with clinical characteristics of each patient that are permanent, that is, do not change over time such as HIV serology status, and create tow related recfiles with 1) data about each liver panel with correspondent date and 2) the medication in use with initial date and end date with the end status (cure, default, death etc); both may be fed with several data from different dates for each patient.

Now ... one common problem with dates is that very often typing mistakes make dates incompatible such as:

1) the second liver panel was collected BEFORE the first.

2) The end of medication was registered BEFORE the beginning or the second medication started BEFORE the end of the first.

To control this sort of mistake is easy with conditional checking when the dates are in the same recfile. But if I make related files the conditional checking with dates should be done in the same field (or different fields) in different records. That is ... I should ask epidata to go in other record with the same key (ID) and check if the collection date is before or after the date of this open record.

The question is ... is this possible? Does anyone have a sugestion to workaround (possibly having all the dates in the main recfile and related file)?

An example:

******** Main qesfile

ID #### name _____ hiv # start <dd/mm/yyyy> end <dd/mm/yyyy> toxicity #

******* First related file - liver panel

ID #### coldate <dd/mm/yyyy> panelnum # alt #### ast ####

****** Secodn related file - medication

ID #### TBdrugs _______ HIVdrugs _______ combstart <dd/mm/yyyy> combend <dd/mm/yyyy> outcome #

Kind regards,

Abraço forte e que a força esteja com você,

Dr. Pedro Emmanuel A. A. do Brasil Instituto de Pesquisa Clínica Evandro Chagas Fundação Oswaldo Cruz Rio de Janeiro - Brasil Av. Brasil 4365 Tel 55 21 3865-9648 email: pedro.brasil@ipec.fiocruz.br email: emmanuel.brasil@gmail.com

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