Characteristics of chronic phencyclidine abusers

Phencyclidine Positivity on Urine Drug Screening in Patients Treated for Alcohol Withdrawal on a Dual-diagnosis Medically Assisted Withdrawal Unit

OBJECTIVES

Little contemporary research has explored phencyclidine (PCP) use in people with alcohol use disorder. Therefore, we sought to determine the prevalence of PCP positivity on urine toxicology screening among patients admitted for alcohol withdrawal, identify correlates of PCP positivity, and investigate PCP positivity's relationship to length of stay (LOS) and risk of facility readmission.

METHODS

This was a retrospective study of patients admitted to a dual-diagnosis medically assisted withdrawal unit for alcohol withdrawal from 2014 to 2019. Univariate tests and logistic regression were used to investigate potential correlates of PCP positivity on admission toxicology screening (primary outcome). Multivariable linear regression models and survival analyses analyzing LOS and risk of readmission (secondary outcomes) were also developed.

RESULTS

Ninety of 3731 patients (2.4%) screened positive for PCP. There were significant associations on univariate testing between PCP positivity and age, race, homeless status, and urine toxicology positivity for amphetamines, benzodiazepines, barbiturates, cocaine, tetrahydrocannabinol, and oxycodone. On multivariate logistic regression, only tetrahydrocannabinol, barbiturates, and cocaine positivity were associated with PCP positivity. Multivariate logistic regression and survival analysis found no statistically significant associations between PCP positivity and LOS or risk of readmission.

CONCLUSIONS

This study provides rare analysis of contemporary data on PCP use among patients undergoing medically assisted alcohol withdrawal. Phencyclidine positivity was uncommon, but use appears considerably higher among this patient population than the general population. There was no significant association between PCP positivity and LOS or readmission risk.

Inpatient treatment of PCP abusers and users

Screening of 155 consecutive admissions to a voluntary, 4-6 week substance abuse inpatient rehabilitation program revealed a 13% prevalence of PCP abuse (defined by DSM-III criteria) and a 23% prevalence of nonabusive PCP use. The 20 PCP abusers were significantly younger (31.6 vs 40.2 years) and had more prior arrests (2.0 vs 0.8) than the 36 nonabusive users, but did not differ in other sociodemographic characteristics. The age range of patients was older than previously reported in the literature, with three PCP abusers (15%) and 15 users (42%) 40 years of age or older. A majority of both abusers (80%) and users (97%) also abused other drugs, including alcohol (57%), opiates (29%), marijuana (29%), and stimulants (18%). The mean length of stay for PCP abusers was 27 days, with 11 completing inpatient treatment. Urine samples were collected upon admission from all patients and assayed for PCP by gas chromatography with N-P detection (sensitivity = 0.1 ng/mL). Patients with initial positive PCP results had follow-up urines collected at least weekly until the PCP assay was negative or they left the treatment program. Twenty-seven percent of patients had PCP detected in admission urine samples, one-third of whom initially denied PCP use. Six patients still had PCP detected after 4 weeks of hospitalization, without evidence of PCP reuse. These findings suggest that PCP abuse and use are common among unselected patients seeking substance abuse inpatient treatment and that they are not confined to the adolescent/young adult age group.

MMPI subtypes for chronic phencyclidine (PCP) abusers

The present study applied empirical clustering procedures to the MMPI protocols of 196 chronic phencyclidine (PCP) abusers. Subjects were randomly divided into two groups, and two methods of cluster analysis, the average linkage method and Ward's hierarchical procedure, were performed. Both cluster methods produced highly comparable results within each group, and the MMPI profiles found in each group were quite similar. Cluster analytic studies of other substance abuse populations are needed in order to replicate the MMPI profile types found in the present study. These investigations would lead to an empirical typology across various substance abuse populations that would depict developmental stages.

Urinary phencyclidine excretion in chronic abusers

Data on usage patterns of 100 hospitalized chronic phencyclidine abusers was collected. Weekly urine samples were monitored using a new gas chromatographic nitrogen detector analysis for PCP. Abusers were found to be, on the average, young males who had used PCP for approximately 40 months (range 12 to 96 months) and approximately 3 to 4 d/week. Except for one subject, urines became negative for PCP within 30 d after last use with a mean of 14 d. There was rapid excretion during the first 9 d followed by a more gradual reduction in urine PCP levels.