Abstract：
BACKGROUND: Nails accumulate the alcohol metabolite, ethyl glucuronide (ETG), and the cannabis metabolite, carboxy- delta-9-THC over 3-6 months. Few studies have examined nail toxicology testing\'s sensitivity and specificity and the agreement between nail testing and self-reported alcohol and marijuana use.
METHODS: In an ongoing clinical trial, 1101 veterans completed initial telephone questionnaires and were then asked to mail nail clippings for substance use analysis. We examined sensitivity and specificity of ETG and carboxy- delta-9-THC in nails compared to self-report of alcohol use patterns (the AUDIT-C) and substance-related harms (alcohol and THC subscales of the ASSIST). We then examined factors associated with discordance between nails and self-report.
RESULTS: Almost two-thirds (707/1101) of respondents mailed in nail clippings. Those with returned nails were disproportionately married, white race, older, and less depressed. At a threshold of 8pg/mg, sensitivity was only.50 to detect risky alcohol use and.49 to detect alcohol-related issues. Sensitivity for marijuana issues was only.61. Specificity was greater than.77 for all measures. Factors associated with positive nails/negative self-report (i.e. false positives) for risky alcohol use on the Audit-C included more pain and being unmarried; false positive nails for alcohol-related issues on the ASSIST were associated with being unmarried and non-Hispanic ethnicity. False positive nails for THC-related issues on the ASSIST were associated with being African American, Hispanic, and having had legal issues.
CONCLUSIONS: At standard cut-offs, nail measures had low sensitivity and higher specificity. The groups who disproportionately submit positive nails/negative self-report could have substance use patterns not adequately captured by self-report, inaccurate self-report due to social pressures, or distinct drug metabolism.
METHODS: In an ongoing clinical trial, 1101 veterans completed initial telephone questionnaires and were then asked to mail nail clippings for substance use analysis. We examined sensitivity and specificity of ETG and carboxy- delta-9-THC in nails compared to self-report of alcohol use patterns (the AUDIT-C) and substance-related harms (alcohol and THC subscales of the ASSIST). We then examined factors associated with discordance between nails and self-report.
RESULTS: Almost two-thirds (707/1101) of respondents mailed in nail clippings. Those with returned nails were disproportionately married, white race, older, and less depressed. At a threshold of 8pg/mg, sensitivity was only.50 to detect risky alcohol use and.49 to detect alcohol-related issues. Sensitivity for marijuana issues was only.61. Specificity was greater than.77 for all measures. Factors associated with positive nails/negative self-report (i.e. false positives) for risky alcohol use on the Audit-C included more pain and being unmarried; false positive nails for alcohol-related issues on the ASSIST were associated with being unmarried and non-Hispanic ethnicity. False positive nails for THC-related issues on the ASSIST were associated with being African American, Hispanic, and having had legal issues.
CONCLUSIONS: At standard cut-offs, nail measures had low sensitivity and higher specificity. The groups who disproportionately submit positive nails/negative self-report could have substance use patterns not adequately captured by self-report, inaccurate self-report due to social pressures, or distinct drug metabolism.
摘要：
背景：指甲积聚酒精代谢产物，乙基葡糖苷酸（ETG），和大麻代谢物，羧基-δ-9-THC超过3-6个月。很少有研究检查指甲毒理学测试的敏感性和特异性，以及指甲测试与自我报告的酒精和大麻使用之间的协议。
方法：在一项正在进行的临床试验中，1101名退伍军人完成了最初的电话问卷调查，然后被要求邮寄指甲剪报以进行物质使用分析。与酒精使用模式（AUDIT-C）和物质相关危害（ASSIST的酒精和THC分量表）的自我报告相比，我们检查了指甲中ETG和羧基-δ-9-THC的敏感性和特异性。然后，我们检查了与指甲和自我报告之间不一致相关的因素。
结果：几乎三分之二（707/1101）的受访者邮寄指甲剪。那些指甲返回的人不成比例地结婚了，白人种族,年长的,不那么沮丧。在8pg/mg的阈值下，检测危险酒精使用的敏感性为.50，检测酒精相关问题的敏感性为.49。对大麻问题的敏感性只有61。所有措施的特异性均大于0.77。与Audit-C上危险饮酒的阳性指甲/阴性自我报告（即假阳性）相关的因素包括更多的疼痛和未婚；ASSIST上酒精相关问题的假阳性指甲与未婚和非西班牙裔种族有关。ASSIST上THC相关问题的假阳性指甲与非裔美国人有关，西班牙裔,有法律问题。
结论：在标准截止日期，指甲测量的敏感性低,特异性高.不成比例地提交阳性指甲/阴性自我报告的群体可能具有未被自我报告充分捕获的物质使用模式，由于社会压力，自我报告不准确，或不同的药物代谢。
方法：在一项正在进行的临床试验中，1101名退伍军人完成了最初的电话问卷调查，然后被要求邮寄指甲剪报以进行物质使用分析。与酒精使用模式（AUDIT-C）和物质相关危害（ASSIST的酒精和THC分量表）的自我报告相比，我们检查了指甲中ETG和羧基-δ-9-THC的敏感性和特异性。然后，我们检查了与指甲和自我报告之间不一致相关的因素。
结果：几乎三分之二（707/1101）的受访者邮寄指甲剪。那些指甲返回的人不成比例地结婚了，白人种族,年长的,不那么沮丧。在8pg/mg的阈值下，检测危险酒精使用的敏感性为.50，检测酒精相关问题的敏感性为.49。对大麻问题的敏感性只有61。所有措施的特异性均大于0.77。与Audit-C上危险饮酒的阳性指甲/阴性自我报告（即假阳性）相关的因素包括更多的疼痛和未婚；ASSIST上酒精相关问题的假阳性指甲与未婚和非西班牙裔种族有关。ASSIST上THC相关问题的假阳性指甲与非裔美国人有关，西班牙裔,有法律问题。
结论：在标准截止日期，指甲测量的敏感性低,特异性高.不成比例地提交阳性指甲/阴性自我报告的群体可能具有未被自我报告充分捕获的物质使用模式，由于社会压力，自我报告不准确，或不同的药物代谢。
