Patient reports of health outcome for adults living with sickle cell disease: development and testing of the ASCQ-Me item banks.

BACKGROUND: Providers and patients have called for improved understanding of the health care requirements of adults with sickle cell disease (SCD) and have identified the need for a systematic, reliable and valid method to document the patient-reported outcomes (PRO) of adult SCD care. To address this need, the Adult Sickle Cell Quality of Life Measurement System (ASCQ-Me) was designed to complement the Patient Reported Outcome Measurement Information System (PROMIS®). Here we describe methods and results of the psychometric evaluation of ASCQ-Me item banks (IBs). METHODS: At seven geographically-disbursed clinics within the US, 556 patients responded to questions generated to assess cognitive, emotional, physical and social impacts of SCD. We evaluated the construct validity of the hypothesized domains using exploratory factor analysis (EFA), parallel analysis (PA), and bi-factor analysis (Item Response Theory Graded Response Model, IRT-GRM). We used IRT-GRM and the Wald method to identify bias in responses across gender and age. We used IRT and Cronbach's alpha coefficient to evaluate the reliability of the IBs and then tested the ability of summary scores based on IRT calibrations to discriminate among tertiles of respondents defined by SCD severity. RESULTS: Of the original 140 questions tested, we eliminated 48 that either did not form clean factors or provided biased measurement across subgroups defined by age and gender. Via EFA and PA, we identified three subfactors within physical impact: sleep, pain and stiffness impacts. Analysis of the resulting six item sets (sleep, pain, stiffness, cognitive, emotional and social impacts of SCD) supported their essential unidimensionality. With the exception of the cognitive impact IB, these item sets also were highly reliable across a broad range of values and highly significantly related to SCD disease severity. CONCLUSION: ASCQ-Me pain, sleep, stiffness, emotional and social SCD impact IBs demonstrated exceptional measurement properties using modern and classical psychometric methods of evaluation. Further development of the cognitive impact IB is required to improve its sensitivity to differences in SCD disease severity. Future research will evaluate the sensitivity of the ASCQ-Me IBs to change in SCD disease severity over time due to health interventions.

Equivalence of mail and telephone responses to the CAHPS Hospital Survey.

OBJECTIVE: To estimate the effect of survey mode (mail versus telephone) on reports and ratings of hospital care. DATA SOURCES/STUDY SETTING: The total sample included 20,826 patients discharged from a group of 24 distinct hospitals in three states (Arizona, Maryland, New York). We collected CAHPS data in 2003 by mail and telephone from 9,504 patients, of whom 39 percent responded by telephone and 61 percent by mail. STUDY DESIGN: We estimated mode effects in an observational design, using both propensity score blocking and (ordered) logistic regression on covariates. We used variables derived from administrative data (either included as covariates in the regression function or used in estimating the propensity score) grouped in three categories: individual characteristics, characteristics of the stay and hospital, and survey administration variables. DATA COLLECTION/EXTRACTION METHODS: We mailed a 66-item questionnaire to everyone in the sample and followed up by telephone with those who did not respond. PRINCIPAL FINDINGS: We found significant (p<.01) mode effects for 13 of the 21 questions examined in this study. The maximum magnitude of the survey mode effect was an 11 percentage-point difference in the probability of a "yes" response to one of the survey questions. Telephone respondents were more likely to rate care positively and health status negatively, compared with mail respondents. Standard regression-based case-mix adjustment captured much of the mode effects detected by propensity score techniques in this application. CONCLUSIONS: Telephone mode increases the propensity for more favorable evaluations of care for more than half of the items examined. This suggests that mode of administration should be standardized or carefully adjusted for. Alternatively, further item development may minimize the sensitivity of items to mode of data collection.