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<br /> 146 AMERIUN JOURNAL OF RESwaA70RY ANl ~TYUL GaE MEDICINE VOl 153 t997
<br /> ji a.0o cocaine smoking during [he follow-Up period, and none initi-
<br /> i ~ sled Intravenous drug abuse. Asthma or ahu chest illness was
<br /> II+ not listed as an txdusionary criterion for participation in the
<br /> ,FI e.ao Tbeon study (lfi, 19). It is unlikely, however, that the presence
<br /> oP rhea lllnasa would hsve accounted for the differentially
<br /> p a m greater rate of foss of lung fundion in the merpuana smokcrs
<br /> ! ~ - _ compared with the nonsmoking or tobacco smoking participand
<br /> ` ~ in the 7beson study (19). Although a higher rate of initiation of
<br /> ~ sso smoking of other illidt substance (ag., crack cocaine, which
<br /> • ' I would be included u a aontoba«o substance) by the nonlobattro '
<br /> s a smokers in the 7Ucson follow-up sample might have contributed
<br /> to the observed excesivc rate of decline among these smokers,
<br /> it it of interest that habitual crack smoking has generally not
<br /> a'+0 so ss ao a se u so ~n associated with impairment in spiromaric indices, at least
<br /> in Dross-sectional stadia (26, 27).
<br />
<br /> ) i To•~ooa_ A9E i7nl Although a "healthy smoker" eff«t might have accounted for
<br /> arVaa anelUllTTaI1T tOeTWl111q
<br /> I Aural ed,r the absence of 8n abnormally rapid decline in lung Function in
<br /> a rev, hex esa oar au the marijuana smoking voluoteert [or the Los Angela study, this
<br /> n 1. Declines in FEV, (In liters) with ors ca+tinuit possibility scems unlikely, ain« tobaxo-smoking participants
<br /> Rya a9c (M ye ) by Y in the same uudy did athibit accelerated declines in FEV„ and
<br /> of toWcco srttoking (never, inlerminem, and ranWuirg), estimated
<br /> i one would not aped that a "healthy smoker" effect would be
<br /> from random eHectsmodel in men. Sops coeffldentslaannual dr confined only to the marijuana smokcrs. Additional eviden«
<br /> cline in FEVI (in mlllttiters) for never, Intermittent, end continuing against a'9teallhy smoker" effect in the Los Angeles marijuana
<br /> tobacco smokers arc Chown at the iattom W the fiyun. smokers is their relatively high prevdenceof symptoms of chronic
<br /> and acute bronchitis at Visit I, which was comparable with the
<br /> prevalence of rhea same symptoms In the tobacco smokcrs In
<br /> the same study (IS), as weE as in the nontobacco (marijuana)
<br /> The reason for the diurepanry between the results of these smokers In the Tucson study (I6).
<br /> two longitudinal stadia Is unclear. One possible rason might A weaknet of the praenl study is the relatively low follow-
<br /> be dw to population sampling differcncea, lira the nndomty up rate (654a), raising the possibility of a diffuential Ions to
<br /> selected 7Uaon sample was mare likely W be representative of follow-up of the sicku panicipants, who might hsvc exhibited
<br /> the marijuana tmoking population at a wdole than was the Los greater rata of decline in lung fundion over time. Although the
<br /> Angela coaveNenceumpie, which may have selectively undo- latter posslbitiry scoot be excluded, the fact that nearly all
<br /> recruited "sicker" smokcrs. Other possible rasons for these participants who could be contacted and did not move out of
<br /> discrepant raulu include differenea in environmental or oc- the area returned for relating, that follow•up rates were com-
<br /> cupatiotulexpoturcs,tx3ncomitancsubstaaceabuse(uidcTrom parable across smoking ategories, and that baseline lung
<br /> tobaceq ouch as stack cosine, pheniyctidine, a huoin), intco- function was similar in those who did and those who did not
<br /> sity and continuity of muiJwna amokirsg,and other host char- undergo follow-up [sting diminishes the likelihood of this ex-
<br /> aderistla, such as allergy and coacomiunt illaesa. With regard planation for the lack of a demonstrable impact of continuing
<br /> to possible eonfoundiog by differences in inlrnalty and/or con- marijuana smoking oolong-function decline, particularly since
<br /> tinuity of marijuana use, it la noteworthy that the muijwna an accelerated decline In FEV, wgs detected in the tobacco.
<br /> stnokusinthepreuotnudywerepartk:u4rlyhavytwrentusas smokingpaniclpantc.
<br /> (manofover3Jointed)andreportedheavydktimeuse(mean Other potential con founding influencesthatmightRaveef-
<br /> of43w36joint-yr,deflnedaalheaumberofjoingpudaytima fasted the results of this longitudinal study of lung function
<br /> the number of Years smoked), and mat (8211 of MT5 and 7341 change include tystcmatic difference in technician or equipment
<br /> o[ MS) continued to smoke marijuana during she rntlrc follow- puformance. However, the same equipment was used through-
<br /> I - up puiod. In conerut, the muijuana etaokm In theTueton co- out the entire study, and all tats were Ixrformcd by two highly
<br /> hors were much lighter amokm 1 jolat/d, on average), and experienced technicians who adhered to a rigorous daily calibra-
<br /> rcpor[ed smash towsr gfetime Intensity o[ ass (man of g3 lion and quality control protocol (26), and were cross trained
<br /> marijuana jolnt•yr, wbrn caleultted as the rumba of joints per in apirometry using Ute same instrtimcnt. Moreover, any instru-
<br /> daY lima tbenumbs of years smoked) (19). Although the authors mart drlR or iatm«haidan variability in tau Prrforman« would
<br /> do ttol specify the conllnWty of marijuana use io thdr Cohort aol be expaled to dlffuentially influence the results only io the
<br /> of everrttatlJwnausen,contUtuingaqultUngmarijuatutmok- marijuanacmokers,tineesubJeasinallsmokingcetegoriawere
<br /> ing did not influence the decrements id lung fundion atitnated tested at similar lima throughout the follow-up period.
<br /> from their model Thus ditfermm fg cvrrnu and tlPtxime atnoum Our failure to flad evidence of progressive tuna dysfunction
<br /> of marijuana ux, or in contlauiry of use dtsriag the course of in the continuing marijuana smokers who we followed contrasts
<br /> fallow-up, do not appar w aceauru for tbs discrepant rcsu)ts with our own oburvstions that the proportion of these smokers
<br /> of the two stadia, dDCa one would not expect the more intense who reported symptoms of chronic bronchitis was comparable
<br /> I, • end prolonged use among the Loa Angela marijuana smokers with that of the tobacco smokers in the acme cohort (IS), and
<br /> ' to have resulted In the much Iowa rate of dalinc in FEV, rela• that many of the continuing marijuana smokers have shown
<br /> v i live to nonsmoking (and even tobacco smoklna) tMn that whidr aA eatemtve hiuopathologic altentiotsa on bronchial mucosal
<br /> was observed in the 7bcaon study. biopaita u the tobatto-only smoker (17, 1g). However, these
<br /> Spedfieally excluded from the psaeat study was individuals simllaritib bdween the efftxtt of habitwl smoking of mariju•
<br /> wfthprealtehtgchronieebatdfsase,Incltrdfagasthmaceahit- anaandtobaaoonehronicrespintorytymptomsandproxima!
<br /> tort' of lntravenOUS drug abuse tx of amoklag substance other Monchlal hlstopathologY do col necesarily imply similar con-
<br /> lhantobaeootutd/ormarljttana.Masova,onlyaaatallminority sequences with rapes to bronchiolar and alveolar injury that
<br /> of the follow-upsample from tbisctihort (12.64.) Initiated cock might lead to smoking•rclated obstructive small airways diuase
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