Comparison of urine to sweat patch test results in court ordered testing 10.1016/803 79-07... Page 1 of 4 Hub B:owse Home Search E.xpoc1 Citation F'Of c297 K) ScienceDirect My ~ttings Scopus Applications My alerts More opllons... ~Shew thumbMIIIIn ou!Wio Forensic Science International Abstract Keywords 1. Introduction 2. Case sludy Comparison of urine to sweat patch test results in court ordered testing -- L-X: Joseph A. Levisk)i' ' .., . 0 . David L Bowennan'', Werner W. Jenkins', Deborah G. Johnson' . JohnS. Levisky', Sleven B. Karch• , El P~.so County Cofor.cJf'.s OffiCe. COIOfoa® Spnc~, CO 8090G, USA 3. O.seussion 3. 1. Sensitivicy 3.2. Specifici ty 3.3. Efficlency 11 B<e:hnvioral Scl..,nc:, Department. Yo1-k Collooe of PP.Ot'I$Yivnn.a, Yot1t. PA. l 740S, USA 'Cdy a11d County of SM Fra~. tiall of Jus.tioa_. 850 Btylrtl Street, San Fmncl<&co, CA 9.i tG3, USA Aeknowledgemenls http·!.'d.-. dci,otg!1 0. 101GIS0-319-073e(01)004<4~ I. MowN C.&iJ OJ Ur~ Usin; 001 P et~kln., & Rtprint& References Q Publishing --., Connect Abstract A fonner cocaine and methamphetamine abuser was continuously monilored with both sweal patch and urine testing for approximately 6 months. Thirteen sweat patches were applied and collected, five were positive for cocaine and/or methamphetamine. but all the urine specimens coltocled were negalive at the Author analytical cut-off levels. The high incidence of falsG positive sweat pat.ch tests in relation to the sensitivity, specifiCity, and efficiency of the sweat patch assay is discussed. Possible mechanisms, which can lead to Training false positive results, are presented. The results of our study raise further questions about the preferential Webcasts use of the sweal patch in detecting new episodes of drug use in formerly chronic drug users. T•ps on how to Keywords get published Sweet patch; Cocaine; Methamphetamine; Sensitivijy; Spedflcity: Efficiency; False positive ~ ~ 1. Introduction Two recent sludies from the Addiction Research Center assessed the sensitivi1y, specifiCity. and efficiency of sweat patch versus urine testing In a group of 44 methadone maintenance patients. For the sw eat patch deteclion of concurrent cocaine use. the sensitlvily was 97.6 %, specificity 60.5%, and efficiency n .7%; and, for opiale use, the corresponding values were 68.6. 86. 1, and 78.6% (1} and (2}. The relatively k1.v values for specificity and effiCiency raise eoncems about whether sweat patch testing is the appropriate methodology to be used when false positives can lead to serious or adverse action against the tesc subject. We r ecenUy had the opportunity lo compare test results of o sequential series o f urine specimens and sweat patches of a probationer, whicl1 were collected continuously over a 6 monlh period. Our fondings 0 Publishing .., Connect Pc.utt"'Cf1119 wnh tht~ Glob.;\l Re ~ntcJt(t:rnmunnt confinn the low specificity and etroclency values repol1ed in the earlier studies. 2. Case study A 35-year-old woman with a history of chronic methamphelamlne and cocaine abuse was ordored by lhe courts fo undergo drug monitoring. She reported uslng bolh drugs interchangeably. When abusing m ethamplletamfne, she consumed, on average, a gram a day. When abusing cocaine. she consumed 2- 4 g per day. Her period o f heaviest drug use occurred d.-ing the 3 months just pnor to the commencement of drug monitoring. The court ordered that she submit to sweat patch monlloring. However, she also eloc!ed to have observed urine specimens colloc!ed and anatyzed for companson. Fig. 1 displays the Inclusive dates the sweat palch was worn with test results along with the dates and resuns of the urine conactions. htto://www.sciencedirect.com/science/article/pii/S03 79073 801 00443 1 3/17/2012 Comparison of urine to sweat patch test results in court ordered testing 10.1016/S0379-07 ... Page 3 of 4 more likely it is lhat drug use will be detected. By definition. a False Positivo Test result does not altor lhe sensitivity value of a tesl. That means lhen. that a tost with a very high degree of sensitivity is not always desirable. ospeciaRy when a falsa positive may result in incarceration Of loss of child custody for the person being tested. 3.2. Specificity Tho specificity of a lest charnctorites the irn:idence of true negative results when a test is applied to subjects known to be free of disease, or Specificity= (~) TN + FP X 100 where TN is true negative and FP is false positive. Unlike sensitivity, specifocity is greatly influenced by the number of false positives. A positive sweat patch test In relation to all negative urine tests while the patch is being wom is defined as a false positive [t] and [2). A specifiCity oft 00% means that if drugs are not used while lhe sweat patch is being worn. both lhe sweat patch test and the urine tesls wiU always be negative. As the numberoffalse positives inereasos, the specificity of the test decreases. Compared to urine testing, the specificity of sweat patch tests fOf cocaine detection is reported to be between 60.5 and 62.9% (11. A test with the highest specificity is desired when the occurrence ol a single False Positive lest can lead to serious and adverse action against the test subject. By this definition, all the positive sweat patches reported for lhis subject were not true positives. bulln fact were false posiUves. 3.3. Efficiency The efficierocy of a test is defined as the percent of all resuhs lha1 are true results, whether positive Of negative. or Efficiency= (TP~l'N) x tOO wh&re Nis lhe total number of tests. If a test is 100% efficient. the test represents lhe true condition all lhe time. An efficiency of <80%. as was the case in lhe clinical stud1es for cocaine and opiate detection [1] and [21. suggests the assay represents true results <80% of lhe time. A lest wilh the highest effici&rocy is desired when both false positive and false negative results are equally serious and damaging. False positives and false negatives present something of a conundrum. False Positive tests damage the probationer. while False Negative tests can be said to damage lhe justice system by allowing drug users to go free. in spite oflhe court.s orders. SWeat patch proponents argue that, in lhe case of cocaine abuse, !he lest has a 97.6% sensitivity. which means lhat the test can be reNed upon to detect drug use when drug use occurs. However. should a test for cocaine detection with a specificity of 60.5% and a 21 .1% false positive rate (1] be acceptable? In monitoring opiate use, Huestis el al. [2] reported a false positive rate of as high as 7.9%. Of 44 monitored subjects. 15 subjects had positive sweat patches during weeks when all corresponding urine tests were negative. During lhe course of the study. one of the test subjects had six positive sweat patches associated wilh aU negative urine tests. and >30% of the participants had at least. one false positive sweat patch at some times during the study. There are several possible mechanisms that might explain the high incidence of false positive sweat patch tests. Licit and illicit drugs are readily identified in skin and adipose tissues of cod avers, and their presence is a luncUon of antemortem deposition, not postmortem redistribution 141 and [5). Juler et al. [6] reponed that chronic cocaine users exhibit prolonged terminal urine hall· lives lor cocaino and metabolites and suggested that cocaine might accumulate in the fatty liuues of the body. Slow release from lhese tissues might accoontlor the prolonged elimination. Subjects who undergo court ordered drug testing undergo testing for a reason. and lhe reason is usually lhat they aro chronic drug users. The time it takes to clear all resio:klal drug from their bodies has never been studied and is not known. There Is also evidence to suggest that drugs can migrate from adipose tissues to the skin surface via extra· circulatory routes [4] and (7]. Others have suggested lhal skin·tcrskin contact is another possible mechanism of drug deposition on the sweat patch. Kidweii[SI demonstrated thai drugs applied to the skin surface remain on lhe skin surface lor days and that simple cleansing does not remove aU lhe drug. Joseph et at [91 Showed thai cocaine per$lsts for several weeks In the stratum cometKn (the outer layer of the skin) in chronic drug users. Individuals who must wear sweat patches have husbands. live.in lovers, and friends who may continue to use drugs. It is not surprising lhat the sweat patch wearer may unknowingly be exposed to these drug sources. Whether one Of all of these mechanisms contribute to the problem is not known, and will never be known until the appropriate studios are undertaken. Untd such studies are undenaken lhe appropriateness of lhe sweat patch methodology. at least for use by lhe cour1S, remains in doubt. Acknowledgements The aulhOfS gratefully acknowledge lhe expert technical assistance of Mrs. Sandy Way. Ms. Cynthia Vislocky and Mrs. Jeanine Jenkins In lhe research and preparation of this manuscripl References [t] K L. Preston, M.A. Huestis, C.J. Wong. A. Umbricht. B.A. Goldberger. E.J. Cone Monitoring cocaine use In substance-abuse-treatment patients by sweat and urine testing J.Anal. Toxiool., 23 (1999). pp. 31~32 1 htto://www.sciencedirect.com/science/article/pii/S03 79073 801004431 3/17/2012 Comparison of urine to sweat patch test results in court ordered testing 10.10 16/S03 79-07 ... Page 4 of 4 ( (2) M.A. Huestis. E.J. Cone. C.J. Wong. A. Umbricht, K.l. Preston Monitoling opiate use In substance abuse Ilea!mont patients with sweat and urine drug testing J. Anal. T<»rico!.• 24 (2000). PJl. 50S-52 I ( (3) R.S. Galan. S.R. Gamblnu. Beyond Norm.-1fity. Tt1o Pr&dlctlva Vaiue and f flicltWlCy of M&dicai Diagnosol\, Wiloy, Now Yo11<. 1975. ( (4) J.A Levisky, D.l. Bowerman, W.W. Jenkins. S.B. Karch Drugs depos~ion in adipose tissue and skin: evidence for an aHemalive soon::e of positive swea1 palchtesls For.Sci.lnl., 1 11 (2000). Jlll, 35-·46 ( (5) JA Lemky. C.l. Bowerman, W.W. Jenl<ios. O.G. JOhnson, S.B. Karcll. Drugs lfl poslrnOriem adipose Wsue11: evidence Q! antemottetn dopo$11100, F<><. Se>encolnt. in press. t [G) RA Jufer, A Wstad ik, S.L. Walsh, B.S. Levina, E.J. Cooe Elimination of cocaine and metabolnes in plasma, saliva, and uriM following repealed oral adminislmllon to human volunteers J. AM!. Toldcol., 2-1 (7) (2000). pp. •67-477 ( [7) M. Bums, R.C. Basel! Monitoring drug u.se with a sweat patch: and experiment with cocaine J . Allol. Toxico!.. 19(1)(1995), pp. 4 1-48 ( [8) DA KldweD. J.C. Holland, S. Alhor.aseb$. Teoting to< drugs of ab\.'SC in salvo and •-t (WbiiShed el1'0tum appears in J. Chtomatog. B. e.orno<l. SCL Appl. 721 (2) ( 1999) 333). J. Chromatog. B. eootl'ed. Sci. Appl. 713 ( I) (1998) 111-135. ( [9) R.E. Joseph Jr.. J.M. Oyler, AT. Wstadillc. C . Ohuoha, E.J. Cooe Drug ti!SOOg wilh alternative matrices 1. Phannacological effect and disposilion of cocaine and ooeleine in plasma, sebun, and stratum corneum J. Anal. Tol<icoi., 22 (1)(1998), pp. 6-17 ( ol. Corresponding author. httn:l/www.sciencedirect.com/science/article/pii/S0379073 801 00443 1 3/ 17/2012