Statistical analyses
To examine associations ranging from diet and heart attack, we utilized Cox proportional problems habits stratified by the age (mo) and you will realize-upwards period to guess RRs and you can 95% CIs. People was indeed put into quintiles off collective average consumption regarding magnesium, potassium, and calcium to attenuate the inside-person adaptation and greatest depict enough time-term consumption ( 18). A mixed mineral diet plan rating out-of magnesium, potassium, and you may calcium supplements was basically determined of the delegating items to for each quintile and you may summing the newest issues. Users regarding reasonable quintile (quintile 1) from magnesium, potassium, or calcium intake gotten step one area each nutrient, participants in the next quintile (quintile dos) received 2 activities, and so on. Collective averages have been determined by firmly taking brand new mean of all of the reported FFQ consumption to the start of per 2-y pursue-right up period. The fresh new collective average consumption was applied in order to assume stroke occurrence out of the time of your own last returned questionnaire before the next follow-upwards duration.
Multivariate activities was indeed modified for age (mo) and you may schedule time (2-y time times) and you can incorporated consumption away from complete opportunity (kcal), alcoholic drinks (g/d), cig, Bmi, physical exercise, adult history of very early myocardial infarction, postmenopausal hormones cures explore, thiazide have fun with, aspirin fool around with, multi vitamin have fun with, and reputation for all forms of diabetes, blood pressure levels, and you can hypercholesterolemia during the standard. To check on having a great linear trend, i assigned for each and every quintile brand new average worth and you can modeled it variable since a continuing variable. I checked-out the possibility departure regarding linearity that with a likelihood ratio try for evaluation out-of a product toward linear name which have a product like the linear identity plus minimal cubic spline transformations ( 19). I plus held analyses that incorporated all step 3 nutrition simultaneously. Magnesium and potassium intakes have been extremely correlated (r = 0.79 in the NHS We; r = 0.73 regarding the NHS II), and you can correlations anywhere between calcium and you will potassium intakes (roentgen = 0.forty-two on the NHS We; roentgen = 0.41 on NHS II), while ranging from calcium and you can magnesium consumption (r = 0.54 on the NHS We; r = 0.56 throughout the NHS II) were modest. The brand new Q sample was utilized to evaluate to your heterogeneity between brand new NHS I and you may NHS II. RRs (±SEs) per quintile out of each cohort was indeed pooled within the repaired-outcomes designs to help you estimate conclusion estimates ( 20). Similarly, brand new up-to-date meta-study adopted basic behavior ( 20) from analysis to have heterogeneity making use of the Q ensure that you playing with fixed outcomes design which will make bottom line rates whenever zero anywhere between-training heterogeneity are obvious; if not an arbitrary-outcomes model was utilized.
To examine the potential effect modification of the association between dietary minerals and stroke risk by age, hypertension, and diabetes, we stratified our multivariate model on age (<60 compared with ?60 y), hypertension (yes compared with no), and diabetes (yes compared with no) and separately tested the significance of an interaction by using a likelihood ratio test for the comparison of the model with interaction terms to the model with only main effects. All P values were 2-sided, and analyses were conducted with SAS 9.2 software (SAS Institute Inc.).
Results
Throughout the 30 y of go after-upwards out of 1980 as a consequence of 2010 on the NHS I and you may twenty two y of go after-upwards from 1989 compliment of 2011 in the NHS II, a maximum of 3780 experience coronary attack circumstances was in fact ascertained. Of those times, 3237 experience shots was noted regarding NHS I (and additionally 1664 ischemic, 544 hemorrhagic, and you may 1029 unspecified strokes), and you will 543 event shots were documented on NHS II (in addition to 186 ischemic, 92 hemorrhagic, and you will 265 unspecified strokes). Age-standard characteristics off study users during the midpoint throughout the follow-upwards from inside the 1994 with the NHS We plus in 1995 having the newest NHS II are provided inside Table step 1. Female which have high mineral intake had been very likely to play with aspirin, multivitamins, and you can postmenopausal hormone therapy, even more actually effective, less inclined to feel latest smokers than simply have been ladies having straight down nutrient consumption. Data for ladies on the NHS I and you will NHS II was shared because i don’t to see a critical between-study heterogeneity (Q-statistic P > 0.05).