Visual hallucinations: a prevalence study among hospice inpatients

The aim of the study was to determine the prevalence of visual hallucinatio ns among hospice inpatients, and the prevalence of a number of possible ass ociated risk factors. One hundred consecutive admissions to St. John's Hospice in Wirral were scr eened for visual hallucinations in a semi-structured interview. The prevale nce of opioid administration, other drugs known to cause hallucinations, br ain tumours, liver metastases, bone metastases, lung metastases, known rena l failure, eye disease, Alzheimer's disease, Parkinson's disease, other neu rodegenerative disorder, psychiatric disorder and epilepsy were also record ed. Subjects were screened for cognitive function using the Folstein mini-m ental state examination (MMSE). Survival times from assessment to death wer e calculated. The results were analysed using arithmetical means with 95% confidence inte rvals (Cl) and odds ratios with 95% confidence intervals. Almost half (47%) the patients had experienced visual hallucinations within the previous month. Hypnagogic or hypnopompic hallucinations of a person s tanding by the bedside were the commonest type. Median survival time for ha llucinators was 15 days (range 0-50 days) and for non-hallucinators was 11 days (range 0-89 days). There was no significant difference in cognitive sc ores between hallucinators and non-hallucinators. Hallucinations were assoc iated with multiple possible risk factors in every case. Hallucinators were more likely to be taking opioids, although the association was not strong (odds ratio 4.48, 95% CI = 1.6-12.19), and were taking larger numbers of po tentially hallucinogenic drugs. It is not clear why some patients on opioid s hallucinate and others do not. Data on the prevalence of various possible risk factors yielded ample material for the planning of future studies.