Health status measurement in Parkinson's disease: validity of the PDQ-39 and Nottingham Health Profile.

We assessed the feasibility and psychometric properties of two commonly used health status questionnaires in Parkinson's disease (PD): the generic Nottingham Health Profile (NHP) and the disease-specific 39-item Parkinson's disease Questionnaire (PDQ-39), from a cross-sectional postal survey of PD patients (N = 81), using traditional and Rasch measurement methodologies. Overall response rate was 88%. Both questionnaires were found feasible, although the NHP performed less well. The PDQ-39 had fewer floor effects and was better able to separate respondents into distinct groups than the NHP, whereas the latter exhibited less ambiguous dimensionality and better targeting of respondents with non-extreme scores. Reliability and validity indices were similar, and potential differential item functioning by age and gender groups was found for both questionnaires. PDQ-39 response alternatives indicated ambiguity. With few exceptions, questionnaire scales were unable to meet recommended standards fully. While preliminary, this study illustrates the need for thorough evaluation of outcome measures and has implications beyond the questionnaires used here. Although promising, both questionnaires warrant further developmental work and stronger support of measurement validity before they could be considered fully suitable for valid use in PD, in particular in earlier stages of the disease.     

Measuring quality of life from the point of view of HIV-positive subjects: the HIV-QL31

Assessment of the quality of life (QoL) of human immunodeficiency virus (HIV)-infected subjects is often based on questionnaires in which the items or questions are not seen to be relevant by patients, nor by the users of the data obtained. It therefore seemed appropriate to return to the issue. The methodological and bibliographical research as well as the consultations we conducted convinced us that the elaboration of a new questionnaire was both necessary and possible. In order to do so, we adopted methodological principles based on the Sickness Impact Profile development methodology. First a bibliographical research was conducted in order to study instruments already used for HIV infection. Then, experts concerned with HIV infection and members of patients' associations were interviewed to assess how opportune the development of a new instrument could be. Following this, a methodology was established for the design and construction of the new instrument. One hundred and eighteen candidate questions were generated from an analysis of the content of 20 patients' interviews, which were subsequently submitted to 102 patients, to obtain finally a set of 31 questions from the interpretation of the results obtained from classic psychometric analysis and also from non-classic methods (item response theory and Rasch model). The concept being measured is the impact of illness being experienced by HIV-infected subjects from their own perspective. The range of health states covered by this questionnaire relates to fairly mild conditions. Rasch analysis of this set of 31 questions (HIV-QL31) shows that it corresponds to one unidimensional construct. A single score can be calculated by simple summation of dichotomous response options. This score is highly reliable (Cronbach's coefficient = 0.93) and is also discriminant regarding the severity of clinical status.     

A comparison of Rasch with Likert scoring to discriminate between patients' evaluations of total hip replacement surgery

The purpose of this study was to examine whether there are advantages in terms of outcome assessment of using Rasch methods of scoring the 12-item Oxford Hip Score (OHS) questionnaire over conventionally Likert scores. As part of a prospective cohort study of total hip replacements in five former regions of England the OHS was sent to patients pre-operatively, at 3 months and 1 year post-operatively. Post-operative data was collected on over 5000 cases. Based on the level of satisfaction with surgery, patients were divided into satisfied and dissatisfied. Analyses were performed to test the relative precision (RP) of Rasch scoring vs. conventionally Likert scores in discriminating the groups experiencing different level of satisfaction. Considerable gains in precision were achieved with Rasch scoring methods when groups were compared 3 and 12 months post-operatively. The results from the current study suggest that in some situations there may be substantial gains in measuring health related outcomes using Rasch-based scoring methods.     

The PaArticular Scales – A new outcome measure to quantify the impact of joint contractures on activities and participation in individuals in geriatric care: Development and Rasch analysis

BackgroundJoint contractures are frequent conditions in individuals in geriatric care settings and are associated with activity limitations and participation restrictions. As such, relevant intervention programs should address these aspects, and the effectiveness of such programs should be determined by assessing improvement in activities and participation. However, no patient-centred and psychometrically sound outcome measures for this purpose are available so far.ObjectivesThe objectives of this study were to develop and to validate a new outcome measure, the PaArticular Scales, to quantify activities and participation in older individuals with joint contractures. Specific aims were (A) to operationalize the content of an International Classification of Functioning, Disability and Health-based standard set towards meaningful questions and to combine them to a questionnaire and (B) to assess the psychometric properties of the developed questionnaire, in detail to evaluate test–retest reliability, objectivity, internal consistency reliability and criterion validity.DesignOperationalization was reached by an expert consensus conference and a subsequent expert Delphi survey. Psychometric properties were assessed in a cross-sectional study.SettingsNursing homes, geriatric rehabilitation facilities.Participants23 experts (nurses, physicians, physical and occupational therapists) participated in the consensus conference and the Delphi survey. A total of 191 individuals with joint contractures (as confirmed by physician, nurse or physical therapist) between 65 and 102 years, living in nursing homes or as patients in geriatric rehabilitation were enrolled in the cross-sectional study.MethodsRasch Partial Credit Modelling.ResultsThe consensus conference and Delphi survey resulted in a questionnaire with 86 items of the International Classification of Functioning, Disability and Health. Test–retest-reliability among those was acceptable (Cohen's weighted kappa: 0.779). The Rasch analysis revealed two independent interval-scaled scales with 24 items for the Activities scale and 11 items for the Participation scale with high internal consistency reliability. Cronbach's alpha was 0.96 for the Activities scale and 0.92 for the Participation scale. Criterion validity was −0.40 and −0.30 for the Activities scale and for the Participation scale, respectively.ConclusionsThe PaArticular Scales, a new patient-centred and psychometric sound outcome measures to comprehensively assess the impact of joint contractures in geriatric care, are available now. These developed scales will serve as primary outcomes in a scheduled evaluation of a complex intervention to improve participation and quality of life in nursing home residents with joint contractures.     

The minimal clinically important difference determined using item response theory models: an attempt to solve the issue of the association with baseline score

ObjectivesDetermining the minimal clinically important difference (MCID) of questionnaires on an interval scale, the trait level (TL) scale, using item response theory (IRT) models could overcome its association with baseline severity. The aim of this study was to compare the sensitivity (Se), specificity (Sp), and predictive values (PVs) of the MCID determined on the score scale (MCID-Sc) or the TL scale (MCID-TL).Study Design and SettingThe MCID-Sc and MCID-TL of the MOS-SF36 general health subscale were determined for deterioration and improvement on a cohort of 1,170 patients using an anchor-based method and a partial credit model. The Se, Sp, and PV were calculated using the global rating of change (the anchor) as the gold standard test.ResultsThe MCID-Sc magnitude was smaller for improvement (1.58 points) than for deterioration (−7.91 points). The Se, Sp, and PV were similar for MCID-Sc and MCID-TL in both cases. However, if the MCID was defined on the score scale as a function of a range of baseline scores, its Se, Sp, and PV were consistently higher.ConclusionThis study reinforces the recommendations concerning the use of an MCID-Sc defined as a function of a range of baseline scores.     

A Quality-Adjusted Life-Year Measure for Multiple Sclerosis: Developing a Patient-Reported Health State Classification System for a Multiple Sclerosis-Specific Preference-Based Measure

BackgroundIncreasingly, generic preference-based measures of health-related quality of life (HRQOL) are used to estimate quality-adjusted life-years to inform resource allocation decisions. Evidence suggests that generic measures may not be appropriate for multiple sclerosis (MS).ObjectivesTo report the first stage in the development of an MS-specific preference-based measure to quantify the impact of MS and its treatment: deriving a health state classification system, which is amenable to valuation, from the 29-item Multiple Sclerosis Impact Scale (MSIS-29), a widely used patient-reported outcome measure in MS.MethodsThe dimensional structure of the MSIS-29 was determined using factor analysis and a conceptual framework of HRQOL in MS. Item performance was assessed, using Rasch analysis and psychometric criteria, to enable the selection of one item to represent each dimension of HRQOL covered by the MSIS-29. Analysis was undertaken using a sample (N = 529) from a longitudinal study of people with MS. Results were validated by repeating the analysis with a second sample (N = 528).ResultsFactor analysis confirmed the two-subscale structure of the MSIS-29. Both subscales covered several conceptually independent dimensions of HRQOL. Following Rasch and psychometric analysis, an eight-dimensional classification system named the MSIS-8D was developed. Each dimension was represented by one item with four response levels.ConclusionsCombining factor analysis with conceptual mapping, and Rasch analysis with psychometric criteria, provides a valid method of constructing a classification system for an MS-specific preference-based measure. The next stage is to obtain preference weights so that the measure can be used in studies investigating MS.     

A Rasch analysis of a questionnaire designed to evaluate psychiatric patient attitudes and knowledge after attending a pharmacist-led patient medication education group

BackgroundThere are many barriers that prevent persons with mental health disorders from achieving remission, including medication nonadherence. Research on the impact of pharmacist-led patient medication education groups on patient attitudes, knowledge and adherence is limited.ObjectiveTo evaluate the reliability and validity of the Medication Attitudes and Knowledge Questionnaire (MAKQ).MethodsA retrospective pre-post questionnaire was distributed to patients. Variables collected included: patient self-reported medication knowledge and attitudes, patient demographics, number of previous psychiatric hospitalizations, whether the patient attended the whole meeting or only a portion, and outpatient pharmacist relationships. Knowledge and attitude items were measured on a 4-point scale with a range of options from “Agree” to “Disagree.” Rasch analysis was conducted to ensure all items measured the same construct and to assess scale and item reliability and validity. Additionally, the Rasch technique evaluated the change in each person's self-perceived attitudes, knowledge, and confidence in self-managing medications from pre- to post-intervention if the data fit the model. A z-test was used to evaluate gaps in content validity.ResultsSixty patients responded to the MAKQ over the 16-week data collection period. Analysis showed that the 4-point rating scale was not useful and that negatively worded items should be eliminated. Gaps identified in instrument item content were not statistically significant (p > 0.05), indicating comprehensive content validity.ConclusionsMedication attitudes and knowledge items on the retrospective pre-post questionnaire were valid and reliable.     

The NTID speech recognition test: NSRT®

Objective: The purpose of this study was to collect and analyse data necessary for expansion of the NSRT item pool and to evaluate the NSRT adaptive testing software. Design: Participants were administered pure-tone and speech recognition tests including W-22 and QuickSIN, as well as a set of 323 new NSRT items and NSRT adaptive tests in quiet and background noise. Performance on the adaptive tests was compared to pure-tone thresholds and performance on other speech recognition measures. The 323 new items were subjected to Rasch scaling analysis. Study sample: Seventy adults with mild to moderately severe hearing loss participated in this study. Their mean age was 62.4 years (sd = 20.8). Results: The 323 new NSRT items fit very well with the original item bank, enabling the item pool to be more than doubled in size. Data indicate high reliability coefficients for the NSRT and moderate correlations with pure-tone thresholds (PTA and HFPTA) and other speech recognition measures (W-22, QuickSIN, and SRT). Conclusion: The adaptive NSRT is an efficient and effective measure of speech recognition, providing valid and reliable information concerning respondents’ speech perception abilities.     

Rasch analysis of a Spanish language-screening parent survey

The purpose of this study was to evaluate and refine items from a parent survey designed to screen the language skills of Spanish-speaking preschoolers. This investigation applied Rasch modeling to systematically evaluate and identify items that demonstrated favorable qualities.A set of 124 parent survey items was administered to 107 Spanish-speaking parents of preschool age children. Parents completed survey items intended to provide a global measure of preschool language abilities. Rasch analyses of the survey items were conducted using WINSTEPS.Results indicated that 59 items, all vocabulary items, fit the Rasch model. Sufficient unidimensionality was obtained, with the model accounting for 58% of the variance. Item difficulty estimates ranged from −7.43 to 4.12, with a shortage of items at both the lower ability level and at the higher ability level. Analyses of pruned and remaining items identified the type of items that may be most useful for a refined item bank. These results will inform the development of new items for a Spanish language-screening parent survey for preschool age children.