Delirium and its Motoric Subtypes in Critically Ill Adult Patients in Medical Intensive Care Unit

INTRODUCTION: Delirium is a common problem encountered amongst the elderly patients in the ICU. Development of delirium is associated with increased severity of illness, length of stay(1,2) and 6-month mortality(3). Delirium is classified as hyperactive, hypoactive, and mixed of which mixed delirium has been shown to be most common. Patients with hypoactive delirium are usually older(4). The incidence of delirium ranges between 45% and 83% in various studies with higher incidence in patients receiving mechanical ventilation(1,2). The Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) is a validated instrument for assessment of delirium in ICU(3) and delirium diagnosis may be missed when assessment tools are not employed.(5) OBJECTIVES: PRIMARY: To study the incidence and prevalence of delirium in critically ill patients in the first week following admission to the medical ICU of a tertiary care hospital SECONDARY: To assess the incidence of delirium in patients less than 65 years and more than 65 years. To study the association between delirium and occurrence of organ dysfunction, need for mechanical ventilation, ICU mortality. MATERIALS AND METHODS: Following approval from the IEC, a prospective observational study was conducted in the medical ICU. As per the incidence from a reference study(5) a sample size of 357 was obtained. All patients admitted in the ICU for > 48 h were included. All patients were assessed once daily for delirium using the CAM-ICU score during the first seven days of ICU stay and type of delirium was determined from daily RAAS score. APACHE and SOFA scores were documented on admission and patients were followed for the development of organ dysfunction, need for mechanical ventilation and outcomes. RESULT: 358 patients were included in the study of whom 39 patients in coma were excluded. Of the remaining 319 patients, 40.8% (n=130) developed delirium during the first week of ICU stay. The prevalence and incidence of delirium in our study was 83.1% (n=108) and (n=22)16.9%respectively. The most common motoric subtype was hypoactive delirium n=70 53.8% patients. Patients >65 years had a higher incidence of delirium at 49.6%when compared with patients less than 65 years 34.3% (p value 0.006). Inotrope requirement (n= 41) need for mechanical ventilation (n = 39) were associated with a higher incidence of delirium (p value 0.001). Patients with delirium had a significantly higher mortality 17.8% (p value 0.001). Chi-square test was applied to find the association of development of delirium and ICU mortality, organ dysfunction and analyze the association between age and the subtypes of delirium independent sample t-test was used to compare the scores (APACHE). Statistical analyses were conducted using SPSS Version 20.0 for Windows (IBM Corporation ARMONK, NY, USA). CONCLUSION: The prevalence and incidence of delirium at our centre was 83.1% and 16.9%. Hypoactive delirium was the most common motoric subtype of delirium. Patients above the age of 65 years, requiring inotropes and mechanical ventilation had a higher incidence of delirium and this was associated with higher mortality.