Refinement and reduction of the Impact of Psoriasis Questionnaire: classical test theory vs. Rasch analysis

Health-Related Quality of Life in Psoriasis: Literature Review

The assessment of quality of life (QoL) in patients with psoriasis plays a crucial role in understanding the impact of the disease and evaluating treatment outcomes. We provide an overview of the key measures used to assess QoL in psoriasis patients, including both generic and psoriasis-specific instruments. The limitations and strengths of instruments such as the Dermatology Life Quality Index (DLQI), Skindex, and Psoriasis Disability Index (PDI) are discussed, highlighting their psychometric properties and areas for improvement. Furthermore, this review examines the potential of disease-specific QoL measures in providing greater sensitivity to disease-related burden and change compared to generic instruments. However, most of the available psoriasis-specific patient-reported outcome measures need further validation. We aim to provide valuable insights into the importance of using validated QoL measures in clinical practice and research, ultimately contributing to a more comprehensive assessment of the impact of psoriasis on patients' lives and enhancing the evaluation of treatment interventions.

Patient-Reported Outcome Measures for Health-Related Quality of Life in Patients With Psoriasis: A Systematic Review

Importance

Multiple patient-reported outcome measures (PROMs) for health-related quality of life (HRQL) exist for patients with psoriasis. Evidence for the content validity and other measurement properties of these PROMs is critical to determine which HRQL PROMs could be recommended for use.

Objective

To systematically review the validity of HRQL-focused PROMs used in patients with psoriasis.

Evidence Review

Using PubMed and Embase, full-text articles published in English or Spanish on development or validation studies for psoriasis-specific, dermatology-specific, or generic HRQL PROMs were included. Development studies included original development studies, even if not studied in psoriasis patients per Consensus-Based Standards for the Selection of Health Measurement Instruments (COSMIN) recommendations. If a study included multiple diagnoses, more than 50% of patients had to have psoriasis or psoriasis-specific subgroup analyses available. Data extraction and analysis followed the COSMIN guidelines. Two independent reviewers extracted and analyzed the data, including PROM characteristics, quality of measurement properties (structural validity, internal consistency, cross-cultural validity, reliability, measurement error, criterion validity, construct validity, and responsiveness), and level of evidence. PROMs were classified into 3 levels of recommendations: (1) PROM recommended for use; (2) PROM requires further validation; and (3) PROM not recommended for use.

Findings

Overall, 97 articles were identified for extraction. This included 19 psoriasis-specific, 8 skin-specific, and 6 generic PROMs. According to COSMIN standards, most measures identified received a B recommendation for use, indicating their potential but requiring further validation. Only the Rasch reduced version of the Impact of Psoriasis Questionnaire (IPSO-11 Rasch) received an A recommendation for use given that it had sufficient content validity, structural validity, and internal consistency.

Conclusions and Relevance

This study identified a significant lack of information concerning the quality of HRQL measures in psoriasis. This gap in knowledge can be attributed to the fact that traditional measures were developed using validation criteria that differ from the current standards in use. Consequently, additional validation studies in accordance with contemporary standards will be useful in aiding researchers and clinicians in determining the most suitable measure for assessing HRQL in patients with psoriasis.

Development and psychometric analysis of the student-teacher relationship scale - short form

The purpose of this study is the construction and validation of an Italian Short Form version of the Student-Teacher Relationship Scale (STRS; Fraire et al., 2013). The analyses were conducted on 1256 students and 210 teachers. The STRS is a self-report measure assessing teachers' perception of the quality of their relationship with students ranging from preschool to third grade. The items were selected from the original Italian adaptation of the regular STRS (Pianta, 2001) through Rasch (1960/1980) analysis, which allowed us to identify a subset of items with proven psychometric properties. The STRS-SF consists of two subscales: Conflict (eight items) and Closeness (six items). Results indicate that the 14-item instrument shows good internal consistency (α>0.80), high correlations with the scales from the regular STRS (r > 0.90) and equivalence across gender.

Patient-reported outcome measures in psoriasis: the good, the bad and the missing!

As a long-term condition, psoriasis demands significant personal and professional input for optimal self-management. Low levels of well-being and high levels of psychological distress in patients with psoriasis are associated with reduced resources for self-care. Patient-reported outcome (PRO) measures can be used to assess physical, social and psychological functioning in order to guide treatment. In this article, we systematically reviewed the development and validation of existing PRO measures. PubMed (Medline), PsycINFO and CINAHL were searched systematically using predefined search terms. The search was limited to articles in the English language relating to human subjects. Articles were selected for full review through explicit inclusion/exclusion criteria. PRO measures were critically reviewed in accordance with the published guidelines and theory on the development and validation of PROs. The search identified 967 abstracts; 71 of these articles met the criteria for full review. In these 71 articles, 45 PRO measures were found: 16 were specific to psoriasis, 21 assessed other dermatological conditions and eight were developed for generic nondermatological health conditions. The review revealed several limitations of the existing measures, including: (i) a composite structure assessing multiple, poorly-defined concepts; (ii) a lack of evidence for face and content validity; (iii) a failure to include both patient and clinician perspectives and requirements and (iv) a lack of evidence regarding the feasibility and acceptability for patients and physicians. No single PRO measure with adequate evidence of validity, reliability and sensitivity to change captures patient well-being in psoriasis. A valid, sensitive, specific and acceptable PRO that assesses the full impact of psoriasis on well-being is needed for the comprehensive clinical management of psoriasis.

Validation of a new tool to assess health-related quality of life in psoriasis: the PSO-LIFE questionnaire

Background

Several questionnaires have been used to measure health related quality of life (HRQoL) in patients with psoriasis, few have been adapted for use in Spain; none of them was developed specifically for the Spanish population. The purpose of the study was to validate and assess the sensitivity to change of a new questionnaire to measure HRQOL in patients with psoriasis (PSO-LIFE).

Methods

Observational, prospective, multicenter study performed in centers around Spain. Patients with active or inactive psoriasis completed the PSO-LIFE together with other Dermatology Quality of Life Index (DLQI) and Psoriasis Disability Index (PDI). A control group of patients with urticaria or atopic dermatitis was also included. Internal consistency and test-retest reliability of the PSO-LIFE were assessed by calculating Cronbach’s alpha and Intraclass Correlation Coefficient (ICC). Validity was assessed by examining factorial structure, the capacity to discriminate between groups, and correlations with other measures. Sensitivity to change was measured using effect sizes.

Results

The final sample included for analysis consisted of 304 patients and 56 controls. Mean (SD) age of psoriasis patients was 45.3 (14.5) years compared to 38.8 (14) years for controls (p < 0.01). Cronbach’s alpha for the PSO-LIFE was 0.95 and test-retest reliability using the ICC was 0.98. Factor analysis showed the questionnaire to be unidimensional. Mean (SD) PSO-LIFE scores differed between patients with psoriasis and controls (64.9 [22.5] vs 69.4 [17.3]; p < 0.05), between those with active and inactive disease (57.4 [20.4] vs 76.4 [20.6]; p < 0.01), and between those with visible and non-visible lesions (63.0 [21.9] vs. 74.8 [23.9]; p < 0.01). The correlation between PSO-LIFE and PASI scores was moderate (r = −0.43) while correlations with DLQI and PDI dimensions ranged from moderate to high (between 0.4 and 0.8). Effect size on the PSO-LIFE in patients reporting ‘much improved’ health status at study completion was 1.01 (large effect size).

Conclusions

The present results provide substantial support for the reliability, validity, and responsiveness of the PSO-LIFE questionnaire in the population for which it was designed.

Development and preliminary validation of the PC-SAD5, a screener-derived short depression severity measure

BACKGROUND

The prevalence of depressive disorders is high among patients with skin disease. The PC-SAD is a 37-item self-administered depression screening questionnaire that has been validated in dermatological patients.

OBJECTIVE

The aim of this study was to develop and validate a brief depression severity instrument derived from the PC-SAD that can be used to assess severity and monitor ongoing clinical course.

METHODS

Two patient samples participated in the study: 72 adult dermatological inpatients and 73 adults attending six primary care practices. Psychiatric assessment included the Structured Clinical Interview for DSM-IV and an 18-item version of the PC-SAD; moreover, dermatological patients completed the Patient Health Questionnaire depression scale (PHQ-9), while primary care patients were administered the Montgomery-Asberg Depression Rating Scale (MADRS). A subset of five PC-SAD items showing the best psychometric properties were selected, and the reliability and validity of the resulting instrument (PC-SAD5) were examined.

RESULTS

The PC-SAD5 showed satisfactory internal consistency in both samples. There was a high correlation between PC-SAD5 and PHQ-9 and MADRS scores. Multiple regression analysis revealed a gradient of PC-SAD5 scores from patients with no mental disorder, those with milder forms of depression, to those with Major Depressive Disorder. Similar results were observed for the 18-item version of the PC-SAD.

CONCLUSION

The availability of valid and reliable continuous measures of depression severity derived from the PC-SAD extends its field of application from depression screening to use as a follow-up measure of depression severity in routine clinical practice. A validated very short instrument such as the PC-SAD5 may have substantial clinical value.

A revised short version of the depression questionnaire

BACKGROUND

The Depression Questionnaire (QD) is an instrument designed to measure depression in an inpatient-rehabilitation setting. This study proposes a reduced version of the original 24-item QD, to make it better suited to the characteristics of patients in this setting.

METHODS

The study population consisted of 801 individuals admitted to cardiac rehabilitation (564 males and 237 females) who had validly completed the original version of the QD. Data were analyzed first through confirmatory factor analysis and then using logistic models.

RESULTS

Factor analysis of QD-24 items form, confirmed the plausibility of the monofactorial solution, both for males and females. Factor analysis combined with clinical observation suggested the possibility of reducing the QD to 17 items. Two further items were eliminated through use of simple logistic models. We thus obtained a shortened 15-item version of the QD (QD-R) that maintains a good index of separation (0.80), that is, good capacity to discriminate between individuals with different levels of depression, and a good item-trait interaction (chi(2)153=165.37, P>0.05). A second confirmatory factor analysis applied to the 15-item monofactorial model confirmed the validity of this shortened version of the instrument. The QD-R scores significantly correlated with metres walked during the 6 minute walking test (r=-0.316; P<0.01).

CONCLUSION

Combined use of confirmatory factor analysis and simple logistic models together with observations drawn from clinical experience constitutes a valid method for shortening a questionnaire while at the same time maintaining, if not improving, its psychometric properties. The QD-R, seems adequate to how much is required in rehabilitation to point out the outcome, in case of variation of depression, easily to fill in by the debilitated individual or elderly, mainly because some item excessively influenced by the pathology or the hospital context were removed.

Use of Rasch methodology to develop a short version of the health related quality of life for eating disorders questionnaire: a prospective study

Background

To confirm the internal structure of the Health Related Quality of Life for Eating Disorders version 2 questionnaire (HeRQoLEDv2) and create and validate a shortened version (HeRQoLED-S).

Methods

324 patients with eating disorders were assessed at baseline and one year later (75.6% of whom responded). We performed a confirmatory factor analysis of the HeRQoLEDv2 using baseline data, and then a Rasch analysis to shorten the questionnaire. Data obtained at year one was used to confirm the structure of the HeRQoLED short form and evaluate its validity and reliability.

Results

Two latent second-order factors -- social maladjustment and mental health and functionality -- fit the data for the HeRQoLEDv2. Rasch analysis was computed separately for the two latent second-order factors and shortened the HeRQoLEDv2 to 20 items. Infit and outfit indices were acceptable, with the confirmatory factor analysis of the HeRQoLED short form giving a root mean square error of approximation of 0.07, a non-normed fit index and a comparative fit index exceeding 0.90. The validity was also supported by the correlation with the convergent measures: the social maladjustment factor correlated 0.82 with the dieting concern factor of the Eating Attitudes Test-26 and the mental health and functionality factor correlated -0.69 with the mental summary component of the Short Form-12. Cronbach alphas exceeded 0.89.

Conclusions

Two main factors, social maladjustment and mental health and functionality, explain the majority of HeRQoLEDv2 scores. The shortened version maintains good psychometric properties, though it must be validated in independent samples.

Maugeri Respiratory Failure questionnaire reduced form: A method for improving the questionnaire using the Rasch model

PURPOSE

The Maugeri Respiratory Failure questionnaire (MRF-28) is the first instrument specifically developed for use with chronic respiratory failure (CRF) patients. The 28 items were selected using classical test theory. The purpose of the current analysis was to further refine the questionnaire using item response theory, specifically, the Rasch model analysis.

METHODS

Three hundred and seventeen CRF patients (mean aged 66.7 yrs; Male 219, Female 98) completed the MRF-28 health status measure. Data were collected through the self-report questionnaire and analyzed using 1-parameter logistic models by means of RUMM software.

RESULTS

The 28-item questionnaire has good psychometric properties in terms of discriminant power because the Person Separation Index is 0.896. However, the item-trait interaction was not good as shown by the total-item Chi-square (chi(2)(112), p<0.001). Removing two items that did not fit the Rasch model well, produced a minor improvement in Person Separation Index to 0.899 and the item-trait interaction improved (chi(2)(104), p = NS). In the preliminary analysis we identified 21 patients who were outliers; when they were excluded the distribution of the residuals, according to the Kolmogorov-Smirnov statistics, was normal and factor analysis of the item residuals showed that the components had similar eigenvalues and no strong correlation with items. These results suggest that the MRF-26 is a unidimensional measure of health-related quality of life impairment for chronic respiratory failure patients.

CONCLUSIONS

A combination of classical psychometric tests and Rasch analysis produced an instrument of moderate size that covers a wide range of effects of CRF and has interval scaling properties.

Quality of life in patients with psoriasis and psoriasis arthritis with a special focus on stigmatization experience

Negative impact of psoriasis and psoriasis arthritis on quality of life is a central consequence of these diseases. Feelings of stigmatization might, for example, already emerge with only small patches of skin being affected. Empirical data indicate that treating dermatologists should address possible negative effects elicited by problematic encounters with the public and in sexual relationships even if the severity of the disease is low, because lesions on invisible parts of the body can already cause serious adverse impairment. Such psychosocial consequences can be reduced by attending a self-help organization and by taking part in an interdisciplinary patient education program led by dermatologists.

The reduced Impact of Psoriasis Questionnaire has good psychometric properties in Italian patients

BACKGROUND

A recent refinement study suggested that a Rasch reduced version of the Impact of Psoriasis Questionnaire (IPSO) of 11 items most adequately assessed the psychosocial impact of US psoriasis patients.

OBJECTIVE

To test whether the IPSO would also behave well in a different population that varies culturally, demographically, and in disease severity.

METHODS

The psychometric properties of the IPSO, using classical test and item response theory (Rasch analysis), were assessed in 805 Italian psoriasis patients.

RESULTS

Patients with more severe psoriasis reported significantly higher impact on their HRQOL (p < 0.001) and the IPSO correlated well with the Skindex-29 (r = 0.74) confirming its validity. The response distribution was adequate for all items, except item 9. The Cronbach's alphas were excellent and the high item-rest correlations confirmed its homogeneity. Principal component analysis demonstrated one dominant factor with an eigenvalue of 4.47 (items loading >0.40). Overall, the 11 IPSO items fitted the Rasch model (p = 0.07) and all items demonstrated a logical threshold order. Of the 11 items, 2 items showed significant individual misfit and only 1 item demonstrated significant differential item functioning for age but none for gender or global severity score.

CONCLUSION

The 11-item IPSO is a valuable psoriasis-specific HRQOL instrument in different populations.