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medscape.
comNov16,2012BOSTON—Anewmeta-analysishasfoundalinear,inverseassociationbetweencardiovasculardiseaseriskandvitamin-Dlevelsuptoacertainpoint,butthenapossible"threshold"effect[1].
DrLuWang(BrighamandWomen'sHospital,Boston,MA)andcolleaguessayintheirreviewthatthemajorityofearliermeta-analyses,aswellasthisone,havefoundanassociationbetweenlowcirculatingvitamin-Dlevelsandincreasedriskofcardiovascularevents.
Butthedose-responsecurvehasnotpreviouslybeenfullydetermined,withsomeresearchsuggestingaU-shapedcurvebetweenthetwo.
"Thedose–responsecurveindicatedthattheassociationwasgenerallylinearacrosstherangeofvitaminDfrom20to60nmol/L,"theystateintheirpaper,publishedonlineNovember13,2012inCirculation:CardiovascularQualityandOutcomes.
"MoreprospectivestudiesandrandomizedclinicaltrialsareneededtofurtherclarifytheassociationbetweenvitaminD>60nmol/LandCVDriskandtoassessthecausalityofobservedassociations,"theynote.
FindingsonDose-ResponseWillHelpInformFutureTrialsWangandcolleaguessaythatwithwidespreadattentiontoapossibleroleofvitaminDinthepreventionofCVD,itwasbecomingincreasinglyimportanttofurtherevaluatethedose–responseassociationbetweenthetwoand"todeterminetheoptimalvitamin-Dlevelthatmayconferpotentialcardiovascularbenefits.
"TheysearchedMEDLINEandEMBASEfrom1966throughFebruary2012forprospectivestudiesthatassessedtheassociationof25(OH)-vitaminDconcentrationswithCVDriskandincluded19independentstudieswith6123CVDcasesin65994participants.
Inacomparisonofthelowestwiththehighestvitamin-Dcategories,thepooledrelativeriskwas1.
52fortotalCVD,1.
42forCVDmortality,1.
38forcoronaryheartdisease,and1.
64forstroke.
And"theseassociationsremainedstrongandsignificantwhenanalyseswerelimitedtostudiesthatexcludedparticipantswithbaselineCVDandwerebettercontrolledforseasonandconfounding,"theyobserve.
Theyalsoassessedthelinearityofthedose–responseassociationbetweenvitaminDandCVDrisk.
Thelatterincreasedacrossdecreasing25(OH)-vitaminDbelowabout60nmol/L,witharelativeriskof1.
03per25-nmol/Ldecrementin25(OH)-vitaminD.
Andalthoughtherewasconsiderableheterogeneitybetweenindividualstudies,stratifiedanalysisfoundthattheinverseassociationwasconsistentinvariousstudysubgroups,too,theynote.
Astrongerassociationwasfoundinstudieswith65nmol/L,sixfoundnosignificantchangeintheriskofCVD,suggestingapossiblethresholdeffect.
"Ourmeta-analysisofprospectiveobservationalstudiesallowsanevaluationofthedose–responseassociationbetweenvitaminDandCVDriskoverabroadrangeofvitamin-Dlevels,whichwillnotonlycomplementfindingsfromongoingrandomizedtrialsbutalsohelptoinformfuturetrialsthattesttheeffectofvitamin-DsupplementsonCVDintermsoftheoptimaldoses,"theyconclude.
Wangetalreportnoconflictsofinterest.
NewMeta-AnalysisSuggests'Threshold'EffectforVitaminDandCVDLisaNainggolanhttp://www.
medscape.
com/viewarticle/774631_print1of22/9/132:44PMHeartwire2012Medscape,LLCCitethisarticle:NewMeta-AnalysisSuggests'Threshold'EffectforVitaminDandCVD.
Medscape.
Nov16,2012.
ReferencesWangL,SongY,MansonJE,etal.
Circulating25-hydroxy-vitamindandriskofcardiovasculardisease.
Ameta-analysisofprospectivestudies.
CircCardiovascQualOutcomes2012;DOI:10.
1161/CIRCOUTCOMES.
112.
967604.
Availableat:http://circoutcomes.
ahajournals.
org.
Abstract1.
http://www.
medscape.
com/viewarticle/774631_print2of22/9/132:44PM