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Polen MR, Whitlock EP, Wisdom JP, et al. Screening in Primary Care Settings for Illicit Drug Use: Staged Systematic Review for the United States Preventive Services Task Force [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US); 2008 Jan. (Evidence Syntheses, No. 58.1.)

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Screening in Primary Care Settings for Illicit Drug Use: Staged Systematic Review for the United States Preventive Services Task Force [Internet].

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3Results

Drug misuse screening and health outcomes (Key Question 1)

We found no evidence addressing the effects on health outcomes of screening to identify and treat drug misuse among asymptomatic individuals in primary care settings. It should be noted that evidence relevant to this key question would require comparing screened versus unscreened individuals. Evidence derived from a context of universal screening comparing individuals who screened positive for drug misuse with individuals who screened negative would not be considered applicable to this key question.

Drug misuse treatment: Overview (Key Questions 4/5/5a)

Table 2 summarizes the more detailed evidence in Table 3 about the 17 fair- or good-quality trials that were included in Key Question 4, 5, or 5a. Trials are listed alphabetically by first author, within drug categories defined by the main drug being treated: opiates, opiates and cocaine, cocaine, and cannabis. Some trials reported outcomes for drugs in addition to the main drug under which they are categorized. The 6 trials examining treatments for opiate misuse 18, 19 23 were conducted among a total of 906 patients, primarily addicted to heroin. All were conducted among young adult or adult populations, with the exception of Guo 2001 21 , which included some adolescents. Five of the six opiates treatments were prescription drugs. One treatment was a comprehensive, intensive psychosocial intervention. 20 One trial (Bernstein 2005) 24 evaluated a counseling intervention to decrease opiate and cocaine use among 1175 primary care patients. Among the six trials of cocaine misuse in 650 patients, 25 30 five tested prescription drug treatments and one 26 examined an acupuncture treatment. All were conducted among young adult or adult populations. The four trials of cannabis misuse in 1170 patients 31 34 all involved counseling interventions. All were among young adults and adults, except McCambridge (2004, 2005) 33 , which included adolescents. Follow-up periods ranged from immediate post-treatment assessments to 1-year post-intake, but were less than six months in duration in 12 of the 17 trials. None of the trials was conducted among pregnant women. With the important exception of Bernstein et al., 24 none was conducted among asymptomatic individuals identified through screening for drug misuse in primary care settings.

Table 2. Summary Table - Randomized Controlled Trials of Drug Treatment (Opiates, Cocaine, and Cannabis) for Young Adults and Adults (KQ 4/5/5a).

Table 2

Summary Table - Randomized Controlled Trials of Drug Treatment (Opiates, Cocaine, and Cannabis) for Young Adults and Adults (KQ 4/5/5a).

Table 3. Evidence Table - Individual Articles Pertaining to Drug Misuse Treatment (KQ 4/5/5a).

Table 3

Evidence Table - Individual Articles Pertaining to Drug Misuse Treatment (KQ 4/5/5a).

Drug misuse treatment and health outcomes (Key Question 4)

Fewer than half of the trials in Table 2 reported mental or physical health outcomes after drug misuse treatment. Two of these were opiate trials, 18, 20 three were cocaine trials 25, 27, 29 and two were cannabis trials (Table 2, column 5). Follow-up periods were 4 months or less, and health outcomes were measured by indices of mental or physical health symptoms, rather than diagnosed health conditions. Assadi et al., 18 in a trial of baclofen treatment of opiate dependence, found a significant reduction in depression symptoms in the treatment group at 3 months (although there was no difference in opiate use). Gruber et al. 20 found that a comprehensive psychosocial intervention reduced depressive symptoms, but not anxiety symptoms, a general index of psychiatric severity, or a general index of physical health at 3-month follow-up. Trials of cocaine misuse treatments reported mostly non-significant results for health outcomes. While desipramine was shown in one trial 25 to improve two indices of psychiatric severity, it did not improve depressive symptoms or cocaine use. Of the two cannabis trials, one reported an improvement in anxiety, but not other psychiatric or medical symptoms, using a motivational enhancement counseling intervention, 32 and the other reported no effect of combined cognitive-behavioral and motivational counseling on a general index of psychiatric symptoms. 31

Summary of Key Question 4

The evidence summarized in Table 2 provides little indication that drug misuse treatment improves health outcomes. Most trials did not report health outcomes. None of the evidence came from trials of asymptomatic individuals who were identified through screening for drug misuse in primary care. There was no representation of adolescent or pregnant female populations.

Drug misuse treatment, drug use, and social or legal outcomes (Key Questions 5/5a)

All of the trials in Table 2 reported drug use outcomes, often including both self-reported and biochemical (usually urinalysis) measures of use. These trials provide good evidence that several drugs (methadone, buprenorphine, and naltrexone) reduce opiate use, at least in the short-term. One intensive, psychosocial intervention also reduced heroin use at 3-month follow-up according to self-reports, but not according to urinalysis. Auricular acupuncture 26 and desipramine 28 reduced cocaine use when measured by urinalysis at post-treatment assessments, while disulfiram 30 reduced self-reported, but not biochemically-verified, cocaine use. The three cannabis treatment trials among young adults or adults reduced multiple self-reported measures of cannabis use. Results from the one cannabis trial including adolescents 33 were inconsistent, but nonetheless found significantly more days abstinent in the treatment group. None of the cannabis trials reported separate biochemical measures of drug use outcomes, although some reported high levels of agreement between self-report and urinalysis results (e.g., Marijuana Treatment Project 32 ). The largest single trial 24 tested a motivational counseling intervention conducted by former drug users to reduce opiate and/or cocaine use among 1175 patients in an outpatient medical clinic. Based on analyses of hair samples, the intervention reduced cocaine use and opiate use at 6-month follow-up. Results for combined cocaine and opiate use were marginally non-significant (p=0.052). Bernstein et al. recruited participants by screening asymptomatic primary care patients for opiate or cocaine use, making this trial unique among those in our review.

Only six trials reported intermediate social and legal outcomes. Gruber et al. 20 reported no effects of their psychosocial intervention for opiate misuse on any of several measures of employment, illegal activity, or social functioning at 3-month follow-up. Interim methadone treatment (i.e., during a waiting period before slots in existing methadone treatment programs were available) did significantly reduce illegal activity and the amount of money spent on drugs during a 4-month follow-up period. One cocaine trial (of desipramine treatment) found null results on indicators of employment, illegal activity, and social functioning. 25 Three of the cannabis trials reported significant improvements in cannabis-related problems, 31, 32, 34 and one of these also reported improvement in an employment index. 32

Summary of Key Questions 5/5a

Overall, the evidence in Table 2 indicates that various drug misuse treatments—including pharmacotherapies and behavioral interventions—effectively reduce opiate, cocaine, or marijuana misuse (KQ5). Follow-up periods were typically short, however, rarely being longer than 6 months after intake. All trials were conducted among treatment-seeking, instead of screened, populations, with one exception 24 in which a brief intervention reduced cocaine and opiate use among primary care patients identified through screening for use of these substances. Evidence of treatment effects on other intermediate outcomes was sparser and less consistent, although behavioral counseling interventions for cannabis misuse appear to reduce cannabis-related problems.

Health benefits of decreasing or ceasing drug misuse (Key Question 7)

Nine of the eleven studies which were identified as relevant to the health benefits of cessation or reduced drug use examined opiate, cocaine, or multiple drug misuse among young adult or adult populations, while two addressed cocaine or cannabis misuse among pregnant women (see Table 4). None directly studied adolescent populations. Among the nine studies of young adults or adults, follow-up periods ranged from 6 months (two studies) to 33 years (one study). Injecting drugs was a frequent route of administration (five studies; route not reported or in four studies). Health outcomes in these studies included mortality, indices of physical and/or mental health and functioning, participation in highly active anti-retroviral therapy (HAART), and HIV disease progression in HAART patients. None of the studies was conducted among screened primary care populations.

Table 4. Evidence Table - Relationships Between Stopping or Reducing Drug Misuse and Morbidity or Mortality Outcomes (KQ 7).

Table 4

Evidence Table - Relationships Between Stopping or Reducing Drug Misuse and Morbidity or Mortality Outcomes (KQ 7).

Among young-adult and adult populations, the strongest evidence for health benefits comes from evaluations of the association between stopping opiate (usually heroin) misuse and mortality. In a 15-year follow-up study of 188 persons treated for opiate dependence in a Danish community, Sorensen et al. 35 interviewed the sample 5 years following treatment, identifying groups that had either quit using opiates entirely, still used occasionally, or continued to use daily. The risk of mortality (hazard rate) over the succeeding 10 years (post-interview) was about half as high in the group who had quit, compared to the group who continued daily use [hazard ratio (95% CI): 0.45 (0.2, 0.8)]. These results were adjusted for age, gender, and number of mental health hospitalizations. Mortality progressively increased between those who had become abstinent at 5-year follow-up, those who occasionally used illegal drugs, and those who used illegal drugs daily. Compared to the general Danish population, mortality remained significantly elevated, however, even in the group that had become abstinent [Standard Mortality Ratio (95% CI): 7 (2.4, 17.0) among women, 8 (6.7, 21.6) among men]. The mortality evidence from Sorensen et al. may be considered stronger or more applicable to Key Question 7 than that from most other included studies because the longitudinal data covered three observation points—during treatment, 5 years post-treatment, and 15-years post-treatment—allowing clear temporal ordering between reported reduction of drug misuse and mortality over the succeeding 10 years. Two other studies in adults also observed samples over at least three time points. 12, 36 Hser et al. 12 conducted a 33-year follow-up of 581 male, criminal offender heroin addicts receiving mandatory treatment in a California criminal justice setting in the period 1962 to 1964. Interviews were conducted in 1974-75, 1985-86, and 1996-97. Mortality was ascertained as of the latter two periods, at approximately 22 and 33 years after intake. There was no significant improvement in mortality in current non-users of heroin, compared with current users, at either the 22- or 33-year follow-ups. Cross-sectional analyses at the 1996-97 interview showed that non-users had significantly less disability, depression, and anxiety symptoms than current users, but there was no difference between these groups in proportions with hepatitis, HIV, or STDs. Although the sample of male heroin addicts in the Hser et al. study 12 was selected from a criminal justice-related population, reducing its generalizeability to primary care populations, the study was included here because of the value of its unusually long follow-up period. Fridell and Hesse 36 identified 125 “drug abusers,” two-thirds of whom reported injection drug use, who sought inpatient treatment in Sweden in 1988-89. Among ninety persons interviewed at 5 years post treatment, mortality was ascertained over the next 10 years. Survival analyses showed no significant association between length of time abstinent at 5-year follow-up and mortality. Cross-sectional analyses at the 5-year follow-up revealed higher global functioning and lower global psychiatric severity in persons who had been abstinent for 6 or more months compared with all others. In summary, across the three studies that examined mortality outcomes, only Sorensen 35 showed a reliable longitudinal association between cessation of opiate use and reduced mortality. Cross-sectional results were mixed, with some evidence of better functioning among drug misusers who were abstinent at the time of assessment, compared with continuing drug users.

Four studies 37 40 examined changes in drug misuse or injection practices in relation to adherence to needed medical treatment, to disease progression, or to mortality, among individuals in treatment for HIV. Lucas et al. 37 identified groups of former heroin or cocaine users (no use in past 6 months), never users, and current users among 764 persons who met criteria for HAART. In general, current users were significantly more likely than never users to have never used HAART. Among those taking HAART, current users were less likely to adhere to the medication regimen and had poorer responses to HAART. Former users were more similar to never users than to current users. In a later report from the same study site, Lucas et al. 39 compared the development of new opportunistic conditions among 1851 HIV patients using HAART across groups of non-drug users, intermittent drug users during abstinent periods, intermittent drug users during active use periods, and persistent drug users. During abstinent periods, intermittent users were not significantly more likely to develop new conditions compared to nonusers, but during active drug use periods, intermittent users had significantly higher risk of developing new conditions (about double that of nonusers). Mortality among intermittent users was intermediate between that of nonusers and persistent users.

Bouhnik et al. 38 followed 144 drug-injecting HIV patients over 18 months, finding that those who had quit injecting drugs for at least 12 months were significantly less likely to be depressed (symptom score) than those who continued to inject, although HAART participation and responses to treatment did not consistently differ. Moatti et al. 40 examined short-term HAART adherence among 164 HIV-positive injecting drug users, finding that adherence among individuals who had quit injecting drugs for the past 6 months or more was not significantly different from adherence among patients on buprenorphine maintenance treatment; in contrast, adherence among active injecting drug users was significantly lower than among patients in treatment. In a sample of 393 individuals who had injected drugs in the past 10 years, Knowlton et al. 41 found significantly lower odds of having depressive symptoms at 1-year follow-up among those who had stopped using all drugs versus those who continued to use. Gossop et al. 42 took a different approach in conducting cluster analyses of factors at intake among 478 persons beginning methadone treatment who participated in 1-year follow-up. Four clusters were identified based on drug use patterns both at intake and follow-up; the two clusters showing improved drug use patterns tended to have improved physical and mental health index scores at 1 year relative to the non-changing clusters. In summary, these six studies all found some associations between reduction or cessation of drug misuse and a variety of health outcomes. All but one of the studies 39 were limited by analyses of behavioral changes between only two time points, producing essentially cross-sectional results in which the timing of changes in drug use were contemporaneous with changes in health indicators.

Two studies assessing health outcomes associated with cocaine misuse were conducted among pregnant women. Shankaran et al. 43 examined patterns of cocaine and marijuana use (separately) during pregnancy in relation to weight, length, and head circumference of infants at birth. Patterns of drug use were identified by mothers' reports following live birth, based on reported drug use during two six-month time periods: the 3 months before pregnancy and the first trimester, and the second and third trimesters. Five patterns were examined across the two time periods: consistently high, consistently moderate, consistently low use, increasing use, and decreasing use. A group-matched comparison group of non-users of cocaine or opiates was identified. Results showed that no marijuana use pattern was related to any of the birth outcomes, compared to non-drug users. Consistently low cocaine use was associated with lower birth weight, and consistently moderate cocaine use was associated with smaller head circumference, compared to non-drug users, but no dose-response relationship was apparent, and decreasing cocaine use was not related to any of the three outcomes. In an earlier, smaller study (N=115), Chasnoff et al. 44 compared pregnancy complications and birth outcomes among women who were: a) exposed to cocaine in the first trimester only; b) exposed to cocaine throughout pregnancy; or c) not exposed to drugs or alcohol during pregnancy. Cocaine exposure throughout pregnancy was associated with more preterm deliveries, lower birth weights, being small for gestational age, and placental abruption than cocaine exposure limited to the first trimester exposure or no exposure. Neonatal weight and length were significantly lower among those who used cocaine throughout pregnancy compared to non-users, but were not significantly different for first trimester-only users. Both cocaine-exposed groups tended to have worse scores on a neonatal behavioral assessment scale than the non-exposed infants. In summary, evidence from these studies is limited to two small studies and mixed with regard to benefits of reducing or quitting drug use during pregnancy, with Shankaran et al. 43 finding little association between drug use patterns and birth outcomes, and Chasnoff et al. 44 finding that stopping cocaine use after the first trimester is associated with improvement in some outcomes, but not others, compared to a continuously exposed group.

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