| Contraception discontinuation [message #9365] |
Sun, 20 March 2016 12:46  |
ASharma
Messages: 6
Registered: February 2016
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I am trying to recreate contraception discontinuation rates- table 7.9 and 7.10 in Nepal DHS 2011; I have used calendar data to derive the rates but for some reason even the number of episodes are not matching with the Nepal 2011 report. Please help.
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| Re: Contraception discontinuation [message #9602 is a reply to message #9552] |
Wed, 20 April 2016 14:19  |
Trevor-DHS
Messages: 802
Registered: January 2013
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Senior Member |
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I don't have too much experience with life tables in Stata, but analysis expert Sarah Bradley wrote recently for another user:
"My suggestions for replicating DHS results are:
1. Reshape vcal_1 and vcal_2 into files where the unit of analysis is the episode of contraceptive use (potential multiple episodes j per woman i). It sounds like this isn't a daunting task for you, but if you run into trouble with this step, please let Trevor and I know, as we're working on standard events-based files.
2. Calculate durations of use from the start and end of each episode of use. Note that DHS standard is to use a window of observation that is 3-62 months prior to interview, censoring the most recent 3 months prior to interview, dropping left-truncated episodes, and including episodes of use that began >62 months before interview as late entries into the life table. We describe this in somewhat excruciating detail in the methodological appendix in the recent Guttmacher Report on Contraceptive Failure.
3. For associated-single decrement rates (as in the Guttmacher report), try -sts list-. Note that this doesn't support pweights. I use iweights and calculate the SEs in alternative ways.
4. For multiple-decrement rates (as in DHS final reports, STATcompiler), I like -stcompet-. The documentation on this in Stata Journal is quite good.
A caveat: -ltable- in Stata assumes that nax = n/2, i.e. that discontinuations occur in the middle of the month. The DHS standard is to assume that discontinuations occur at the end of the month, so -ltable- will produce slightly different estimates than -sts list- which assumes that failures occur at the end of the month."
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| Re: Contraception discontinuation [message #9753 is a reply to message #9621] |
Fri, 13 May 2016 05:04 |
Sarah B
Messages: 23
Registered: June 2013
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Hi Anu,
Most contraceptive discontinuation rates are calculated for specific methods, so sterilization is not an issue. When all methods are combined, though, episodes of sterilization that began during the window of observation are included in the denominator, and in the numerator in the very rare case of discontinuation.
As explained in the Guttmacher report, episodes of use that began prior to the window of observation are excluded from analysis, regardless of the method used, because we do not have a start date/duration for the episode.
I haven't gone through your code in detail, but noticed one issue below that will make your #s not match the results in the DHS final report. Your window of observation is set for the past 5 years prior to interview, i.e. months 0-59 prior to interview. DHS (and the Guttmacher report referenced below) censors the 3 months prior to interview because women may not recognize they are pregnant in the first 0-2 months of pregnancy. To avoid underestimation of contraceptive failure due to unrecognized pregnancies, we use months 3-62 prior to survey as the window of observation. So I think you want:
gen callen = v018 + 3 + 59
gen begin = v018 + 3
Cheers,
Sarah
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| Re: Contraception discontinuation [message #12411 is a reply to message #9753] |
Thu, 11 May 2017 16:46 |
Osmara
Messages: 1
Registered: May 2017
Location: São Paulo
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Dear Trevor and Forum members
I'm analyzing data about contraceptive discontinuation and have some doubts about how to organize my dataset: I'm using data from local survey in Brazil and I have used Calendar data.
Looking at Polis et al. (2016) in Appendix A: Calculation of failure rates, I check that "episodes of contraceptive used began before your observation period but within the calendar period, you include the episode as a late entry into the life table, using only the months of contraceptive use that ocurred within the 3-62 months period of observation". I have around 68-72 months of observation for each woman, and I'll analyze only 3-62 months too. So I need exclud months 63-72. In what moment I exclud these episodes? It's whem I'm preparing my dataset or doing analyze? Could you please assist me with obtaining the Stata command to do this exclusion.
I would greatly appreciate any assistance you could offer. Thank you.
Osmara
Osmara
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