Effect of delirium motoric subtypes on administrative documentation of delirium in the surgical intensive care unit

Abstract

This study compares the proportions of surgical intensive care unit (ICU) patients with delirium detected using the Confusion Assessment Method for the ICU (CAM-ICU) who received administrative documentation for delirium using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes, stratified by delirium motoric subtypes. This retrospective cohort study was conducted at a surgical ICU from 06/2012 to 05/2013. Delirium was assessed twice daily and was defined as having ≥1 positive CAM-ICU rating. Delirious patients were categorized into hyperactive/mixed and hypoactive subtypes using corresponding Richmond Agitation Sedation Scales. Administrative documentation of delirium was defined as having ≥1 of 32 unique ICD-9-CM codes. Proportions were compared using Pearson's Chi-square test. Of included patients, 40 % (423/1055) were diagnosed with delirium, and 17 % (183/1055) had an ICD-9-CM code for delirium. The sensitivity and specificity of ICD-9-CM codes for delirium were 36 and 95 %. ICD-9-CM codes for delirium were available for 42 % (95 % CI 35-48 %; 105/253) of patients with hyperactive/mixed delirium and 27 % (95 % CI 20-34 %; 46/170) of patients with hypoactive delirium (relative risk = 1.5; 95 % CI 1.2-2.0; p = 0.002). ICD-9-CM codes yielded a low sensitivity for identifying patients with CAM-ICU positive delirium and were more likely to identify hyperactive/mixed delirium compared with hypoactive delirium.

Evaluation of algorithms to identify delirium in administrative claims and drug utilization database

“…Two studies that examined ICD diagnosis codes only in patients with confirmed delirium reported sensitivity of 9% and 28% . Other studies reported sensitivity of 3–36%, specificity of 85–99%, PPV of 38–83%, and NPV of 67–90% . In our study, the same list of 32 ICD‐9 codes and related ICD‐10 codes used by Bui et al .…”

“…For algorithms based on ICD diagnosis codes, delirium was considered present if any of the following 32 explicit (i.e., including the term “delirium”) or implicit ICD‐9 diagnosis codes (e.g., “encephalopathy”) were used among the in‐hospital discharge codes (Table S1). In claims data from October 1, 2015, the corresponding 52 ICD‐10 diagnosis codes were used . For algorithms based on antipsychotics use, delirium was considered present if any antipsychotic drugs were used; in our study, we found that only haloperidol, olanzapine, and quetiapine had been prescribed.…”

“…Low sensitivity of claims‐based algorithms results in underestimation of the prevalence of delirium, in particular, delirium without hyperactive psychomotor symptoms or mild delirium. Previous studies reported that 1–22% of hospitalized patients had explicit or implicit ICD diagnosis codes indicating delirium and that 4–9% of patients received antipsychotics during non‐psychiatric hospitalization . These estimates are substantially lower than the rates of delirium diagnosed according to the reference standard: 11–29% in medical wards, 11–51% in surgical wards, and 19–82% in the intensive care unit .…”

“…Moreover, they are unavailable in healthcare utilization databases (e.g., claims data or hospital clinical data repository) that contain information on diagnoses, procedures, medications, and laboratory tests. The International Classification of Diseases (ICD) diagnosis codes that explicitly or implicitly indicate delirium variably under‐diagnose the condition . Some studies have attempted to use antipsychotic drug administration as an indicator of delirium, but the accuracy of this approach alone or combining ICD diagnosis codes and antipsychotics use has not been well established.…”

Patterns of Potentially Inappropriate Bladder Antimuscarinic Use in People with Dementia: A Retrospective Cohort Study

“…, 290.12, 290.13, 290.20, 290.3, 290.41, 290.42, 290.43, 290.8, 290.9, 293.0-293.9, 348.30, 348.31, 348.39, 349.82, 780.0, 780.09, 780.02, 780.97)[25][26][27].…”