(886): How many questions does it take to obtain valid and precise estimates of the impact of pain on a patient’s life?

Abstract

The assessment of pain and its impact requires reliable and valid patient-based assessment tools. Computerized adaptive testing (CAT) is a novel approach to pain assessment. This study examined the precision and validity of pain-impact scores and response burden from simulated CAT administration of a bank of 45 items. Adults (n=1,500) randomly sampled from the general US population via telephone or internet completed a questionnaire consisting of pain items from widely-used instruments (SF-36, Nottingham Health Profile, Sickness Impact Profile, McGill Pain, Oswestry Low Back Pain, Brief Pain Index, Aberdeen Back Pain, EuroQOL, Health Insurance Experiment, Fibromyalgia Impact Questionnaire, Short MusculoSkeletal Function Assessment). A 45-item bank meeting the assumptions of an item response theory (IRT) model was calibrated on a common metric and a series of CAT administrations with varying fixed lengths (2, 5 and 7 items) or varying precision levels were simulated. Each simulated CAT score was compared to a score (theta) based on the entire item bank. High correlations were observed between the CAT estimates and the theta score (.90-.99). The theta score showed the best measurement precision (95%CI:1.6-15.6) at all score levels; the CAT-2 showed the least precision (95%CI:5.8-14.8); the CAT-5 (95%CI:3.3-12.6) and CAT-7 (95%CI:2.8-12.7) provided acceptable precision levels, while dramatically decreasing the length of the measure. All assessments were most accurate in the middle range of the scale and showed substantial increases in measurement error towards the end points. Taking into account the variations in precision observed across CAT simulations, on average 5-6 items were needed to reach acceptable levels of precision, representing an 89% reduction in respondent burden. All CATs significantly discriminated (p<.001) between people with and without chronic pain in the hypothesized way. The results of this study suggest that it takes 5-6 tailored items to produce a valid and precise patient-reported score of pain impact. The assessment of pain and its impact requires reliable and valid patient-based assessment tools. Computerized adaptive testing (CAT) is a novel approach to pain assessment. This study examined the precision and validity of pain-impact scores and response burden from simulated CAT administration of a bank of 45 items. Adults (n=1,500) randomly sampled from the general US population via telephone or internet completed a questionnaire consisting of pain items from widely-used instruments (SF-36, Nottingham Health Profile, Sickness Impact Profile, McGill Pain, Oswestry Low Back Pain, Brief Pain Index, Aberdeen Back Pain, EuroQOL, Health Insurance Experiment, Fibromyalgia Impact Questionnaire, Short MusculoSkeletal Function Assessment). A 45-item bank meeting the assumptions of an item response theory (IRT) model was calibrated on a common metric and a series of CAT administrations with varying fixed lengths (2, 5 and 7 items) or varying precision levels were simulated. Each simulated CAT score was compared to a score (theta) based on the entire item bank. High correlations were observed between the CAT estimates and the theta score (.90-.99). The theta score showed the best measurement precision (95%CI:1.6-15.6) at all score levels; the CAT-2 showed the least precision (95%CI:5.8-14.8); the CAT-5 (95%CI:3.3-12.6) and CAT-7 (95%CI:2.8-12.7) provided acceptable precision levels, while dramatically decreasing the length of the measure. All assessments were most accurate in the middle range of the scale and showed substantial increases in measurement error towards the end points. Taking into account the variations in precision observed across CAT simulations, on average 5-6 items were needed to reach acceptable levels of precision, representing an 89% reduction in respondent burden. All CATs significantly discriminated (p<.001) between people with and without chronic pain in the hypothesized way. The results of this study suggest that it takes 5-6 tailored items to produce a valid and precise patient-reported score of pain impact.