Re: st: Creating drugs combination

[Nick Cox <njcoxstata@gmail.com>]

If I understand this correctly at least  some values of your drug  
variables are composite strings of form similar to "a+b", "a+b+c", etc.

If so, then you can't count distinct drugs except by parsing those  
strings.

I would think in terms of -split-, -reshape long-, -duplicates drop-  
and -by id: gen ndrugs = _N-.

Nick

On 13 Sep 2012, at 16:39, Michele Santacatterina <miksanta@hotmail.it>  
wrote:

> Dear StataList,
>
> I have an issue. I am trying to create, from a HIV database, a  
> variable containing the value of different drug combinations (name  
> regimen) and the number of drugs (number of drugs)$
>
> ID      treatstart      treatstop       drug             
> name_regimen    number_of_drugs
> 2       24-Aug-95       14-Nov-97       ZDV             ZDV 
> +3TC                 2
> 2       24-Aug-95       13-Feb-03       3TC
> 2       7-Aug-96        14-Nov-97       LOV             ZDV+3TC 
> +LOV             3
> 2       14-Nov-97       15-Jun-00       IDV             3TC+IDV 
> +d4T             3
> 2       14-Nov-97       13-Feb-03       d4T
> 2       15-Jun-00       13-Feb-03       IDV             3TC+IDV 
> +RTV             3
> 2       15-Jun-00       13-Feb-03       RTV
>
> Patient 2 started ART at 24-Aug-95 with ZDV+3TC and at 7-Aug-96, LOV  
> was added to the treatment becoming ZDV+3TC+LOV. At 14-nov-97 he  
> finished with ZDV and LOV and he started with $
>
> If I run the command
>
> by infcare_ID treatstart, sort: gen n_trt = _n
>
> for the number of drugs, i obtain at 7-Aug-96 just one drug (LOV)  
> and not 3 as I should have (ZDV+
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