BACKGROUND: Psychosis is common in advanced Parkinson’s disease and in some dementias, such as Alzheimer's disease. Antipsychotics are commonly used to treat psychosis associated with dementia, although the FDA issued a black box warning of mortality risk in these patients. Assessing the risk of mortality associated with antipsychotics requires correct identification of patients with psychosis, which may be challenging, particularly in automated health care databases where diagnosis code algorithms are used.
OBJECTIVES: To identify coding algorithms used to identify patients with psychosis associated with dementia in recent literature.
METHODS: A targeted literature review, from 2008 to date, was conducted in PubMed to identify code algorithms used to identify psychosis associated with dementia in studies assessing the mortality risk among these patients treated with antipsychotics.
RESULTS: Of 324 records identified in our search strategy, 32 articles were selected for review. Of them, 28 articles were excluded because they relied on medication use and 2 were excluded because they identified psychosis using patient-reported questionnaires. Two included studies conducted in the US identified psychosis using the following ICD-9-CM codes: 293.81-2, 297.0- 3, 297.8-9, 298.0-4, 298.8-9, 368.16, and 780.1. We expanded our search by conducting a literature search in PubMed to identify studies assessing the epidemiology of psychosis in dementia. We identified 3 additional articles: 1 US study defined psychosis with the presence of one of the following ICD-9-CM codes: 780.1, 292, 292.1, 293.81-2, 297, 298.3-4, 301.0. Another study conducted in Taiwan identified psychosis with ICD-9 codes 295.00-298.9, and 299.10-11. A third US study used the definition: ≥ 1 medical claim with a diagnosis of psychosis (298.0, 298.1, 298.4-298.9), hallucinations (293.82, 368.16, 780.1), or delusions (293.81, 297.1).
CONCLUSIONS: The majority of studies analyzing mortality in patients with dementia treated with antipsychotics did not identify psychosis with diagnosis codes, and most did not account for delirium or agitation. Only five studies used coding algorithms to identify psychosis in patients with dementia. Most of these studies used similar codes to identify hallucinations (293.82 and 780.1) and delusions (293.81 and 297). However, these studies also included different, including nonspecific, codes to identify psychosis. A validated coding algorithm updated to ICD-10-CM to identify psychosis related with dementia is recommended.
