Mild-to-Moderate Psoriasis - part 2 pdf

PQOL itemswere rated on an 11-point Likert-type scale where 0¼ ‘‘not at all,’’ 5¼ ‘‘somewhat,’’ and 10 ¼ ‘‘very much.’’ APPLICATION OF THE ORIGINAL PQOL The 41-item PQOL was utilized in

Localized psoriasis (less than 10% BSA involvement) that is tant to topical therapy or is disabling (e.g., palmarplantar psoriasis)

resis-
One of the serious subtypes of localized psoriasis (less than 10%BSA involvement) that has a possibility of progression (e.g., gener-alized pustular or erythrodermic psoriasis), or

Clinical evidence of psoriatic joint disease as assessed by thepatient and physician

Part 4 Feasibility of Phototherapy

Lastly, the feasibility and clinical appropriateness of phototherapy is rapidlyevaluated in six simple questions

Determination of Candidacy for Systemic Therapy

Using the responses to the ‘‘yes’’ or ‘‘no’’ questions in Part 3 and Part 4 ofthe Physician Assessment, the candidacy for systemic therapy is determined

If the physician has checked at least one of the shaded boxes in bothPart 3 and Part 4, then the patient is a candidate for systemic therapy

BACKGROUND ON THE PQOL-12

The PQOL-12 is a valid and reliable subset of the original PQOL, a 41-item,self-administered, disease-specific questionnaire initially developed in 1991

by John Koo, M.D.(3–5) The questionnaire items were generated throughfocus groups in which patients discussed their experiences with psoriasis Anationwide, population-based, demographically balanced sample of 50,000households was then used to identify 599 psoriasis patients in the UnitedStates for item testing The 41-item PQOL was qualitatively divided intotwo domains: psychosocial and physical The psychosocial domain consisted

of 22 items requiring patients to characterize the impact of psoriasis on theirinteractions with friends and family and on their feelings and self-percep-tion The physical domain consisted of 19 items requesting that patients ratethe impact of their psoriasis symptoms on their daily activities PQOL itemswere rated on an 11-point Likert-type scale where 0¼ ‘‘not at all,’’

5¼ ‘‘somewhat,’’ and 10 ¼ ‘‘very much.’’

APPLICATION OF THE ORIGINAL PQOL

The 41-item PQOL was utilized in a clinical study of 71 patients with stableplaque psoriasis on up to 20% of their total BSA, and plaque elevation

of at least moderate severity (6) Psychometric analysis of the 41-itemPQOL showed satisfactory reliability, validity, and responsiveness to change(3) Items within each domain had approximately equal variances and

contributed equally to the total score and were, therefore, summed withoutweighting The 41-item PQOL was scored by computing the mean scorefor each domain, on a 0 to 10 scale.

DEVELOPMENT OF THE PQOL-12

The 41-item PQOL was too lengthy for frequent use in clinical practice, andthe assumption of two domains (psychosocial and physical) was not entirelyappropriate as analyses following its development had shown overlapamong these domains A shorter instrument measuring unique constructswas needed for clinicians and researchers who were interested in assessingpsoriasis-specific Health-Related Quality-of-Life (HRQOL) in clinicalresearch or daily practice Factor analysis techniques were used to refinethe 41-item PQOL The resulting questionnaire (PQOL-12) consisted of 12items measured on one domain Psychometric properties of the PQOL-12were assessed using data from an multicentered office-based study (Study 1)and a randomized clinical trial (Study 2)

STUDY 1: MULTICENTERED OFFICE-BASED STUDY

Item Reduction

The PQOL was refined and reduced to a 12-item instrument using data from

an office-based study of 483 patients stratified by physician-rated psoriasisseverity at three U.S psoriasis centers from October 2001 to May 2002(7,8) Severity was assessed by the investigator at the time of enrollment,and included a psoriasis area severity index (PASI) evaluation Physicianscompleted several different symptom severity assessment questionnaires:global assessment of severity ranging from mild, moderate, and severe based

on the BSA affected, PASI, overall lesional assessment (OLA) and severity

of symptoms experienced by patients In addition, each patient was asked tocomplete a demographic questionnaire, the PQOL, the Dermatology LifeQuality Index (DLQI) and a disease severity assessment Patient-rated sever-ity was defined as mild, moderate, or severe with the question ‘‘How wouldyou rate the overall severity of your psoriasis, during the past month?’’For this study, one compound question from the 41-item PQOL [i.e.,item #22: How much does your psoriasis interfere with making social con-tacts and relationships?] in the psychosocial domain was divided into twoquestions, creating a 42-item instrument A combination of qualitativereview and factor analysis was used to refine the questionnaire Observa-tions were randomly assigned to an exploratory or confirmatory data set.The exploratory data set (n¼ 301) was used to reduce and refine the existingPQOL instrument and the confirmatory data set (n¼ 182) was used to testthe reliability of the findings from the exploratory analysis Each PQOL

item was evaluated for missing values, mean scores, floor/ceiling effects,reading level, translatability, and applicability to all patients Qualitativecriteria were applied by assessing items for redundancy, wording, andmeaning/conceptual characteristics Factor analysis was used to assessthe factor structure and item loadings on factors An item-retention gridconsisting of all analytical parameters was created to evaluate all item para-meter estimates simultaneously and to facilitate the item-reduction decisionprocess Once reduced, all analyses performed on the exploratory data set(i.e., descriptive and factor analysis) were repeated on the revised question-naire (i.e., PQOL-12) using the confirmatory dataset The confirmatoryanalyses yielded results consistent with the exploratory analyses.

Validity and Reliability

Following the confirmatory analysis, the psychometric properties of thePQOL-12 were assessed using Multitrait Analysis Program-Revisedfor Windows1PC-SAS1–based software7 (9) and the pooled data set(n¼ 482) The PQOL-12 demonstrated desirable psychometric properties.Ninety-nine percent of respondents completed the survey providing evidence

of appropriate item responses of the PQOL-12 The PQOL-12 also exhibitedsupport for the assumptions of summated scales The PQOL-12 items hadapproximately equal variances (so they could be summed) and contributedequally to total score (i.e., no weighting needed) All items demonstrated desir-able item internal consistency by exceeding the criteria of 0.40 correlation withthe total score The instrument also demonstrated good potential for respon-siveness Cronbach’s a was 0.95 and the mean inter-item correlation was 0.62,providing evidence of reliability (Tables 1 and 2) Although the questionnairecould have been reduced even further, some questions that have been deemedimportant in clinical practice were retained Investigation of construct validityindicated that the mean PQOL-12 score was moderately correlated with clin-ical measures, and highly correlated with patient-rated psoriasis severity(r¼ 0.61) and with the DLQI (r ¼ 0.78) (Table 3)

Individual item correlations with overall patient-rated severity rangedfrom 0.40 (‘‘how helpless do you feel with regard to your psoriasis?’’) to0.61 (physical irritation) There were low to moderate correlations withphysician-rated severity A probable explanation for the more modest correla-tions with physician-rated severity was that physicians based their severityassessment on BSA using an ordinal scale (mild <5%, moderate 5–10%, severe

>10%) and lesion morphology that focused strictly on physical characteristics

of the patient’s condition The correlations between individual PQOL-12items and the DLQI items ranged from 0.50 to 0.69 The total PQOL-12 scorewas moderately correlated with OLA (0.38), BSA (0.33), and the PASI (0.36),providing evidence of convergent instrument and construct validity

Mean PQOL-12 scores were calculated for each disease severity level

by both patients and physicians (Table 4) All pairwise comparisons of

PQOL-12 means for both physician and patient ratings of severity in theoffice-based study were statistically significant (p < 0.001), providing evi-dence of discriminant validity.

Responsiveness

The potential for responsiveness was assessed in this office-based sectional study (Study 1) using the PQOL-12 The mean score for thePQOL-12 was 5.03 (SD, 2.76) Only 1.5% of the responses were at the floorand 1% of responses were at the ceiling, indicating that the scale has thecapability to assess both extremes and that the instrument would be capable

cross-of detecting changes during a clinical trial Responsiveness was furtherassessed with the following clinical trial data (Study 2)

STUDY 2: USING DATA FROM THE RANDOMIZED

CLINICAL TRIAL

In Study 2, data from the clinical trial on the 41-item PQOL was used toevaluate psychometric properties of the PQOL-12 Disease severity wasmeasured from both physician and patient perspectives Physicians wereasked to evaluate overall patient discomfort, overall disease severity defined

as mild, moderate, or severe, percent BSA involvement, signs and symptoms

of disease (e.g., pruritis), and overall response to treatment Patients wereasked to complete the 41-item PQOL and an overall evaluation of their dis-ease severity Patient severity was defined as cleared, mild (trace, mild),moderate (moderate), or severe (severe, very severe) with the question

‘‘How would you rate the overall severity of your psoriasis at this time?’’The 12 items of the PQOL were used to retrospectively assess validity,reliability, responsiveness, and the minimally important difference (MID)(10) (i.e., a change in the PQOL-12 questionnaire that would indicate theneed for a change in therapy) The PQOL-12 demonstrated validity andreliability Item-to-total correlations were moderate to high, and Cronbach’s

a was 0.91 Correlations of the total PQOL-12 score and the individualPQOL-12 items with the clinical measures were moderate for all measures(Table 5) The PQOL-12 also discriminated among physician and patient-rated severity at baseline and at end of treatment (Table 4)

Responsiveness

In Study 2 (using the clinical trial data retrospectively), the responsivenessassessment included examination of floor and ceiling effects, differences inseverity levels, and treatment effects There were no floor or ceiling effectsobserved for the PQOL-12, indicating that it has the capability to detectimprovement and decline in this patient population Mean PQOL-12 scores

were calculated for each disease severity level by both patients and cians Both at the baseline and at the end of treatment, differences betweenseverity levels were generally 1 or 2 points for both physician and patientratings (Table 4).

physi-Table 5 Spearman Correlations Between PQOL-12 Items and Clinical Measures(Study 2)

Question

Diseasediscomfort

Diseaseseverity

PercentageBSA Pruritis

In the past four weeks

How self-conscious do you feel

with regard to your psoriasis?

0.34a 0.29a 0.43a 0.30aHow helpless do you feel with

regard to your psoriasis?

How embarrassed do you

feel with regard to your

psoriasis?

How angry or frustrated do you

feel with regard to your

psoriasis?

To what extent does your

psoriasis make your

How much does your psoriasis

impact your overall emotional

well-being?

Overall, to what extent does

your psoriasis interfere with

your capacity to enjoy life?

During the past four weeks, how

much have each of the

following been affected by

Significant at the a ¼ 0.05 level.

Abbreviations: PQOL-12, 12-Item Psoriasis Quality-of-Life Questionnaire; BSA, body surface area.

MINIMALLY IMPORTANT DIFFERENCE

The MID was assessed using an anchor-based approach The MID is thesmallest (or minimal) change in an HRQOL measure that is consideredmeaningful (or important) by either a clinician or a patient (8) A techniqueadapted from Juniper et al was used to calculate the MID using data fromStudy 2 (8) Three anchors or measures of improvement were investigatedincluding: patient-rated disease severity, physician-rated disease severity,and physician-evaluated global response to treatment A difference of 1.24points was observed between those who improved and those who reported

no change in the patient-rated severity The difference in the means of thesetwo groups was statistically significant, indicating an important and statis-tically significant difference between these two groups Differences betweenthose who improved and those who did not experience a change was calcu-lated as 1.14 using the physician rating of global response to treatment,although the means were not statistically significant between these twogroups In contrast, differences between physician ratings of severity weresmaller (0.39) and the means of improvers and patients who did not experi-ence change were not statistically significant This finding suggests that a0.4-point change may be sufficient to distinguish these groups on this mea-sure In summary, these results suggest that the MID for PQOL-12 score isabout 1 point, although it may be as low as 0.4 points

TEST–RETEST RELIABILITY OF THE PQOL-12

Although the above study designs precluded assessment of the test–retestreliability of PQOL-12, preliminary analyses from subsequent researchindicate that the test–retest correlation of PQOL-12 exceeds 0.80 whenconducted over a period of 2 to 30 days

CALCULATING THE PQOL-12 SCORE WITHIN THE KMPI

To be consistent with the desire for the KMPI to be a simple and easily usedtool within clinical practice, the calculation of the PQOL-12 score for usewithin the KMPI differs from how the PQOL-12 score is reported above.Whereas the PQOL-12 score above ranges from 0 (best) to 10 (worst) and

is calculated by taking the mean of the item scores, the scoring for thePQOL-12 within the KMPI does not involve calculating mean item scorebut rather uses a simple sum of the item scores for a score that ranges from

0 (best) to 120 (worst)

As the burden of psoriasis on a patient’s health-related and specific quality-of-life is determined by a range of variables unique to eachpatient’s disease symptoms and life-circumstances, a comprehensive andpractical approach was employed to determine a PQOL-12 score criterion

psoriasis-for use within Part 3 of the KMPI Qualitative review of the data fromStudy 1 and Study 2 along with quantitative analyses (i.e., exploratory clus-ter analysis) was conducted to identify if there was a natural ‘‘cut-point’’between patients with mild and moderate psoriasis that was relativelystable over the various patient- and physician-rated severity measures Inaddition, we sought to balance this with a cut-off point where a therapeuticintervention might be expected to have an impact on psoriasis-specificquality-of-life, while also accounting for the minimum important difference

on the PQOL-12, which is approximately 1 to 2 points Analysis results cated that such a cut-off point might be as low as a score of 25 using thescoring method for the PQOL-12 within the KMPI, however, clinicalopinion suggested the use of a more conservative 50 points for the finalinstrument Further research is needed to better understand the minimumpoint where treatment might positively impact psoriasis patients based ontheir PQOL-12 score

or the examination room prior to being seen by the physician Similarly,the physician assessment takes approximately five to seven minutes to com-plete and the resulting instrument can become part of the patient’s medicalrecord for reference at subsequent patient visits

The KMPI is unique in providing a complete evaluation of the patient’sdisease status-incorporating assessments of psoriasis-specific quality-of-lifewith a validated questionnaire (PQOL-12), psoriasis severity and psoriaticjoint disease

The KMPI alerts the physician and patient of the need to assesshealth-related quality-of-life and joint-related symptoms in the clinical eva-luation of psoriasis and determines the suitability (or otherwise) for systemictherapy in individual patients

The KMPI has the potential to improve physician–patient cation by involving the patient in characterizing their disease and its impact

communi-on their lives

CONCLUSION

The KMPI is a practical assessment tool that dermatologists can quicklyand easily use in their daily practice to help guide them in identifying

patients with psoriasis who may be candidates for systemic therapy, as well

as to justify these decisions to third-party payers

REFERENCES

1 Krueger G, Koo J, Lebwohl M, et al The impact of psoriasis on quality of life.Results of a 1998 National Psoriasis Foundation patient-membership survey.Arch Dermatol 2001; 137:280–284

2 Krueger GG, Feldman SR, Camisa C, et al Two considerations for patients withpsoriasis and their conicians: What defines mild, moderate, and severe psoriasis?What constitutes a clinically significant improvement when treating psoriasis?

J Am Acad Dermatol 2000; 43:281–285

3 Koo J, Kozma CM, Reinke K The development of a disease-specific naire to assess the quality of life for psoriasis patients: an analysis of the reliability,validity, and responsiveness of the psoriasis quality of life questionnaire Derma-tologie Psychosomatik 2002; 3:171–179

question-4 Feldman S, Koo J, Menter A, Bagel J Decision points for the initiation of temic treatment for psoriasis JAAD 2005; 53(1):101–107

sys-5 Koo J Population-based epidemiologic study of psoriasis with emphasis onquality of life assessment Dermatol Clin 1996; 14:485–496

6 Koo JY, Martin D Investigator-masked comparison of tazarotene gel q.d plusmometasone furoate cream q.d vs mometasone furoate cream b.i.d in the treat-ment of plaque psoriasis Int J Dermatol 2001; 40:210–212

7 Koo J, Menter A, Lebwohl M, et al The relationship between quality of lifeand disease severity: results from a large cohort of mild, moderate, and severepsoriasis patients [abstr] Br J Dermatol 2002; 147:1078

8 Koo J, Kozma CM, Menter A, et al Development of a disease-specific quality oflife questionnaire: the 12-item Psoriasis Quality of Life Questionnaire (PQOL-12).61st Annual Meeting of the American Academy of Dermatology, 2003

9 Ware JE, Harris, Gandek WJ, Rogers BW, Reese PR MAP-R for Windows:multitrait/multi-tem scale analysis software user’s manual, Boston, MA, 1997

10 Juniper EF, Guyatt GH, Willan A, Griffith LE Determining a minimal tant change in a disease-specific quality of life questionnaire J Clin Epidemiol1994; 47(1):81–87