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Joined Mar 2016
Joined Mar 2016


I'm developing and evaluating a number of measurements of OSA related pathology; and comparing them to standard measurements (i.e. AHI) in their ability to predict long-term outcomes (in this case, all-cause mortality). As such, I'm attempting to replicate elements of previously published analyses.

I have a couple of questions to tie up a few loose ends:

  1. Sample size of available data for SHHS1:

The samples size for SHHS1 was approximately 6400. However, the data available through NSSR has approximately 5800. Was this because one of the parent cohorts didn't have data sharing permission built into the original consent?

  1. What are the "primary" variables coding prevalent cardiovascular disease at baseline?

Similar information appears to be coded in variables from different sourcers. In particular, there are the cardiovascular history variables from: (i) the parent cohorts (i.e. prev_mi, prev_stk, etc.) - However, approximately 20% of patients have missing data for these variables (presumably from whole parent cohorts). (ii) The questionnaires from patient recruitment to SHHS (i.e. MI15, STROKE15, etc.).

The latter is appealing because data is available for almost all the patients; but I'm not sure if these were considered the primary information about cardiovascular disease history in the original study design. Ultimately, it is probably most important that the variables I use are consistent with previous literature. Do you know which ones match the variables used in key publications (Particularly Punjabi et. al., Plos Med., 2009, and Redline et al., AJRCCM, 2010)?

  1. Which AHI?

Similarly, which AHI variable was used by these key publications? My guess based on methods sections of papers is ahi_a0h4, but it would be great to confirm if possible.

Cheers and thanks,

Phil Terrill