25(OH)D concentration) and Chinese participants (HR, 1.67 [95% CI, 1.07-2.61]). However, there was no evidence of asso- ciation among black participants (HR, 0.93 [95% CI, 0.73- 1.20]) or Hispanic participants (HR, 1.01 [95% CI, 0.77-1.33]). Evaluation of the association of 25(OH)D with CHD risk using splines and race/ethnicity-specific 25(OH)D quintiles simi- larlyrevealedthatsignificantassociationswerelimitedtowhite and Chinese participants ( Figure and Table 4 ). Sensitivity Analyses For the more restricted hard CHD outcome (n = 216 events), associations of low serum 25(OH)D concentration were of stronger magnitude for white and Chinese participants and were null for black and Hispanic participants (eTable 2 in Supplement). Similar results were observed when mean annual 25(OH)D concentration was replaced with untrans- formed 25(OH)D concentration and models were adjusted for season of blood draw, when participants with incident CHD events during the first 12 months of follow-up were excluded, and in analyses restricted to participants with good, very good, or excellent self-reported health statuses (eTables 3, 4, and 5 in Supplement). Discussion In this multiethnic, community-based cohort of adults without clinical cardiovascular disease, low serum 25(OH)D concentra- tion was associated with increased risk of adjudicated incident CHDeventsamongwhiteorChineseparticipantsbutnotamong blackorHispanicparticipants.Differencesinassociationsacross race/ethnicity groups were consistent for both a broad and re- stricted definition of CHD and persisted after adjustment for known CHD risk factors. We examined CHD events as our study outcome in part be- cause low 25(OH)D concentration has been consistently associ- ated with increased CHD risk in observational studies of white participants. 2-10 However,fewofthesestudiesincludedsubstan- tial numbers of multiracial participants. Among those that did, thenumberofmultiracialparticipantswasinsufficienttotestfor racialheterogeneity(n = 332), 5 theanalyseswerecross-sectional, 7 ortheoutcomewaslimitedtosubclinicalcardiovasculardisease. 9 Further analyses of racial differences in the associations of 25 (OH)D with CHD are needed to confirm our results. Until such studiesareavailable,resultsofstudiestestingassociationsofcir- culating 25(OH)D concentration with CHD or related outcomes inpredominantlywhitepopulationsshouldnotbeextrapolated to multiracial populations. Table 2. Coronary Heart Disease Incidence Rates per 1000 Person-Years Event a All Participants (n = 6436) White Participants (n = 2501) Chinese Participants (n = 784) Black Participants (n = 1750) Hispanic Participants (n = 1401) No. of Events IR No. of Events IR No. of Events IR No. of Events IR No. of Events IR Any CHD event b 361 7.38 167 8.61 27 4.41 94 7.22 73 7.02 Myocardial infarction 156 3.15 76 3.86 10 1.61 29 2.2 41 3.9 Angina c 182 3.71 90 4.62 16 2.6 41 3.15 35 3.36 Resuscitated cardiac arrest 24 0.48 9 0.45 1 0.16 11 0.83 3 0.29 CHD mortality 63 1.22 21 1.03 4 0.62 23 1.68 15 1.36 Abbreviations: CHD, coronary heart disease; IR, incidence rate.
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