The minimal clinically important difference of the Richmond Agitation-Sedation Scale in patients with cancer with agitated delirium

BACKGROUND: The Richmond Agitation-Sedation Scale (RASS) is commonly used to assess psychomotor activity; however, to the authors' knowledge, its minimal clinically important difference (MCID) has not been determined to date. The objective of the current study was to identify the MCID for RASS using 2 anchor-based approaches. METHODS: The current study was a secondary analysis of a randomized controlled trial to compare the effect of lorazepam versus placebo as an adjuvant to haloperidol for persistent agitation in patients with delirium. The primary outcome was change in RASS (10-point numeric rating scale ranging from -5 [unarousable] to +4 [combative]) from baseline to 8 hours after treatment administration. The sensitivity-specificity and within-patient change methods were used to identify the MCID, with the anchor being patient comfort after the study intervention as perceived by caregivers and nurses. RESULTS: A total of 90 patients were randomized and 58 (64%) received the study medication for restlessness/agitation (mean baseline RASS, 1.6). A total of 23 caregivers (61%) and 23 nurses (55%) perceived that the patient was more comfortable after treatment. Using the sensitivity-specificity method, the optimal RASS reduction was ≥4 points according to both caregivers (sensitivity of 61% and specificity of 80%; area under the curve, 0.71) and nurses (sensitivity of 73% and specificity of 84%; area under the curve, 0.78). The RASS cutoff value based on the within-patient change method was similar (-4.2 for caregivers and -4.0 for nurses). CONCLUSIONS: For patients with persistent restlessness/agitation, a reduction of ≥4 points in RASS was considered to be the MCID for both nurses and caregivers. These preliminary findings may have implications for sample size calculation and the interpretation of treatment effect in future delirium trials. Cancer 2018;124:2246-52.