although we cannot rule out the existence of
unmeasured confounders, we adjusted our analysis
for the most important known risk factors for
hypertension and other lifestyle variables such as
smoking, which could act as markers of general
lifestyle. Additional analyses including possible
indications, or contraindications, for NSAID use
did not greatly impact our estimates. Even after
adjusting for other analgesics (non-aspirin analgesics
in the analysis of aspirin, and aspirin in the analysis
of non-aspirin analgesics) the association remained.
Although we validated most of the information in
the questionnaires,18-20 sodium intake is not easily
measured with food-frequency questionnaires and
could partially explain the observed association.
An added limitation is therefore the lack of sodium
measurement through 24 hours urine collection.
Finally, we also face the limited information on
the exposure, since more detailed information on
drug dosage and type of drug, etc, would have been
useful especially in relation to a possible dose-effect
gradient.