Clinical characteristics of cough mixture abusers referred to three substance abuse clinics in Hong Kong: a retrospective study.

OBJECTIVES. Cough mixture is the third most commonly abused substance in patients attending the Prince of Wales Hospital Substance Abuse Clinic. The content of the local cough mixture is not well researched. Paranoid psychosis manifesting as persecutory delusions and derogatory hallucination, as well as mood symptoms, is common in these patients. The natural history and outcome of such psychoses associated with cough mixture abuse are not well known. This study aimed to address these questions. METHODS. This was a retrospective study of cough mixture abuse in Hong Kong. Case records of cough mixture abusers currently receiving treatment at the 3 substance abuse clinics at the Prince of Wales Hospital, Alice Ho Miu Ling Nethersole Hospital, and the North District Hospital were retrieved for data collection. The patients' demographic data, duration and intake pattern of cough mixture, and use of any other drugs were documented. The presenting psychopathology, first urine toxicology results, diagnosis, treatment, number of hospitalizations, and course of the illness were also recorded. RESULTS. A total of 63 patients with the diagnosis of cough mixture abuse were identified in the database; 89% were male. The mean +/- SD age of the patients was 34.4 +/- 6.2 years; 67% were single and 83% were unemployed. The mean +/- SD age of onset of cough mixture abuse was 20 +/- 5 years. Psychiatric symptoms developed a mean +/- SD of 7.6 +/- 6.0 years after onset of abuse. According to the ICD-10 Mental and Behavioural Disorders criteria, the top psychiatric diagnoses were substance-induced psychotic disorder (67%), schizophrenia (19%), depressive disorder (11%), and dysthymia (10%). The most common ingredients in the urine sample at first presentation were promethazine (75%), pseudoephedrine (67%), codeine (60%), ephedrine (57%), zopiclone (17%), and hydrocodone (16%). Additionally, 16% of patients were in the priority follow-up group. The mean +/- SD follow-up period was 6.2 +/- 7.1 years during which there were 3.2 +/- 3.7 episodes of hospitalizations, with a mean +/- SD length of stay in each admission of 25.0 +/- 40.9 days. CONCLUSIONS. Promethazine, ephedrine, pseudoephedrine, codeine, and hydrocodone are the most common ingredients of cough mixture abused in this locality. Psychotic disorders are the most frequent psychiatric diagnosis associated with cough mixture abuse.