affective and sensory dimensions of pruritus severity

8122019 Affective and Sensory Dimensions of Pruritus Severity

httpslidepdfcomreaderfullaffective-and-sensory-dimensions-of-pruritus-severity 17



122 R Zachariae et al

Acta Derm Venereol 88

on different aspects of QoL All of the patients agreed to parti-cipate and completed a questionnaire package The study wasconducted in accordance with the requirements of the localethics committee

Measures

bull A Pruritus Severity Questionnaire listing the 6 sensory descrip-tors (ldquocrawling like antsrdquo ldquoticklingrdquo ldquopinchingrdquo ldquostabbingrdquoldquostingingrdquo and ldquoburningrdquo) and 4 affective descriptors (ldquoun-

bearablerdquo ldquoworrisomerdquo bothersomerdquo and ldquoannoyingrdquo) asdescribed by Yosipovitch et al (12) Each descriptor wasranked on a 4-point Likert scale from 0 = none to 3 = severeTwo independent translations into Danish of the Englishdescriptors were discussed and a preliminary version wasagreed upon This version was back-translated and a finalversion was prepared taking any discrepancies between the2 versions into consideration

bull Severity of pruritus was also assessed on a 100-mm visualanalogue scale (VAS) with end-points anchored by ldquono itchrdquoand ldquoas bad as could possibly berdquo As a comparison measurethe patients were also asked to rate on a VAS the severity ofthe strongest itch after a mosquito bite

bull A short Sleep Quality Questionnaire consisting of 3 modifieditems from the Pittsburg Sleep Quality Index (18) The pa-tients were asked to rate on a 4-point scale (i) how much their

pruri tus had made it difficult to sleep during the past week(ii) how well they had generally slept during the past week(reversely scored) and (iii) whether they had used any sleepmedication during the past week A total Impairment of Sleepscore (0ndash9) was calculated by adding the scores of the 3 itemswith higher scores indicating greater impairment of sleep The

patients were also asked to estimate the average number ofhours they had slept per night during the past week

bull The short 13-item version of Beck Depression Inventory (BDI-13) (19) The short version has been shown to be a reliableand valid screening instrument for depression (20) Tested in a

sample of 3486 Danish women treated for breast cancer (21)the BDI-13 has shown good internal consistency (Cronbachrsquosalpha 083) and validity Scores for each item range from 0to 3 yielding a total depression score ranging from 0 to 39Receiver operating characteristic (ROC) analysis using thesame sample showed that a cut-off of 9 yielded both highsensitivity (986) and specificity (946) for identifying

participants characterized as having moderate-severe depres-sion on the full 21-item BDI

bull The 18-item Brief Symptom Inventory (BSI-18) (22) was usedfor assessing general distress Scores on each item rangesfrom 0 to 4 and a Global Severity Index is calculated withscores ranging from 0 to 72 The suggested cut-off scores fordistress caseness of 10 for men and 13 for women (22) were

used to identify patients with high vs low distressbull To measure QoL impairment directly related to the impact of pruri tus we modified the Dermatology Life Quality Index(DLQI) (23 24) Item 1 referring directly to pain or itchseverity was excluded as this otherwise would artificiallyincrease the association with the pruritus severity measureinvestigated Item 2 which refers to embarrassment due toappearance was excluded together with item 10 which refersto problems related to the treatment of the skin condition asthese items are unrelated to pruritus The remaining itemswere rephrased to refer directly to difficulties due to pruritusReliability was tested in the present sample

bull Questions concerning age disease duration co-morbidityand medication

bull Finally psoriasis severity was assessed by a dermatologistusing the Psoriasis Area and Severity Index (PASI) (25)

Statistical analysis

The dimensional structure of the pruritus descriptors was ana-lysed with an exploratory principal components analysis withvarimax rotation Variables were plotted inspected and testedfor normality BDI-13 and BSI-18 scores were skewed anddeviated significantly from normality (Kolmogorov-Smirnovtest) The variables were successfully transformed using thesquare root (BDI-13) and log-10 (BSI-18) The data for menand women were compared with χ2 tests and t -tests for inde-

pendent samples correcting for multiple comparisons with theBonferroni method (26) Correlations between variables werecalculated and the influence of the 2 different dimensions of

pruritus on depressive symptoms general distress and QoL wasanalysed with multiple hierarchical linear regression analysescontrolling for age sex disease duration disease severity andsleep quality In addition logistic regression was used to test theassociations between pruritus and the risk of being classified ashaving moderate-severe depression as well as general distresscaseness Finally the possible mediating effects of sleep qualityon these associations were explored Baron amp Kenny (27) andKenny et al (29) have defined 4 analytical steps necessary toestablish mediation (i) the independent variable (IV) should bea significant predictor of the dependent variable (DV) (ii) the

IV should predict the mediator (iii) the mediator should predictthe DV when controlling for the IV and (iv) the association

between the IV and the DV should be reduced when controllingfor the mediator Complete mediation of the IVndashDV associationrequires that the IVndashDV association is reduced to zero whencontrolling for the mediator Partial mediation requires the as-sociation to be reduced to a non-trivial size but not to zero Inaddition for each of the 3 DVs the Sobel test was used as adirect test of mediation (28)

RESULTS

Cronbachrsquos alpha of the BDI-13 BSI-18 and the mo-died DLQI were 090 092 and 085 respectivelyindicating good internal consistency in the presentsample The demographic characteristics of the patient

sample including sex age disease severity (PASI)and disease duration are shown in Table I The scoreson the 10 pruritus severity descriptors were analysedwith an exploratory principal components analysis withvarimax rotation The rotation converged in 3 iterationsand conrmed 2 distinct independent factors Factor

1 termed the affective dimension consisted of the 4original affective descriptors described by Yosipovitch

et al (12) ie ldquounbearablerdquo ldquoworrisomerdquo bothersomerdquoand ldquoannoyingrdquo together with 2 of the original sensorydescriptors ldquoburningrdquo and ldquostingingrdquo Factor 2 thesensory dimension consisted of the 4 sensory descrip-tors of ldquocrawling like antsrdquo ldquoticklingrdquo ldquopinchingrdquo

and ldquostabbingrdquo When analysing the non-parametriccorrelations between the scores of each descriptorwith total BDI-13 and BSI-18 scores the originalsensory descriptors of ldquoburningrdquo and ldquostingingrdquo weresignicantly associated with both depressive symptoms(rho 046ndash047 p lt 001) and distress (rho 053ndash055

p lt 001) while the remaining sensory descriptors werenot (rho 010ndash030 ns)



123Subjective dimensions of pruritus severity in psoriasis


Scores on the 6 affective and the 4 sensory items weresummed to an Affective Pruritus Severity (APS) and aSensory Pruritus Severity (SPS) score Sum scores werecalculated as percentage scores Mean affective (APS)and sensory (SPS) scores are shown in Table I together

with mean scores on the pruritus VAS the BDI-13 theBSI-18 the modied DLQI average hours of sleep perweek and total Sleep Quality scores Although womenshowed a tendency to be older have longer disease

duration be more depressed and distressed to scorehigher on APS and to have more sleep impairment

than men no differences reached statistical signicancewith or without correcting for multiple comparisons

Mean VAS pruritus intensity was 65 higher than mean perceived intensity of itch associated with a mosquito bite ( p lt 0001)

Correlations between perceived pruritus measuresage disease severity disease duration sleep quality

and measures of depression and distress are shownin Table II VAS pruritus severity showed signicant positive correlations with several measures includingsleep impairment depressive symptoms distress and

QoL impairment regardless of whether or not perceived pruritus severity of a mosquito bite was controlled for

One exception was that pruritus severity of a mosquito bite was signicantly inversely correlated with PASI

Table I Sample characteristics given as mean with standard deviation (SD) within parentheses were not otherwise stated

Men

(n = 24)

Women

(n = 16) p b Total

Age (years) 507 (131) 585 (125) 007 538 (133)

Psoriasis Area and Severity Index (PASI) score 136 (77) 119 (90) 054 129 (82)

Disease duration (years) 216 (121) 298 (159) 024 248 (141)

Co-morbidity () 550 450 052 500

Pruritus severity (VAS) 745 (254) 851 (196) 017 788 (236)

Perceived severity of mosquito bite (VAS) 504 (340) 443 (341) 058 480 (338)Sensory Pruritus Severity (SPS) 399 (241) 333 (251) 041 373 (244)

Affective Pruritus Severity (APS) 583 (293) 674 (301) 035 619 (296)

Average hours of sleep 58 (15) 63 (16) 030 60 (15)

Total Sleep Quality 35 (26) 44 (19) 028 39 (24)

Depressive symptoms (BDI-13) 82 (75) 89 (61) 073 85 (69)

Moderate-severe depression (BDI-13 ge 9) () 292 313 089 300

Distress Global Severity Index (BSI-18) 114 (130) 158 (149) 032 132 (138)

Distress caseness (BSI-18 ge 10 (men) ge 13 (women)) () 375 500 043 425

Pruritus-related quality of life (DLQI)a 87 (59) 89 (63) 089 88 (60)

aModied DLQI omitting irrelevant items and item relating directly to perceived itch and phrasing items to relate to impairment of QoL due to itch b p-values presented are uncorrected for multiple comparisons

VAS visual analogue scale BDI-13 short 13-item version of Beck Depression Inventory BSI-18 18-item Brief Symptom Inventory DLQI Dermatology

Life Quality Index

Table II Correlations between pruritus severity demographic and disease characteristics sleep quality depression and distress

R

Sensory Pruritus

Severity (SPS)

Affective Pruritus

Severity (APS)

Pruritus severity 1

(VAS)

Perceived

severity of

mosquito bite

(VAS)

Pruritus severity 2

(VAS)a

Pruritus severity (VAS) 030 065 ndash ndash ndash

Perceived severity of mosquito bite (VAS) 008 034 023 ndash ndash Sensory Pruritus Severity ndash 041 030 008 029

Affective Pruritus Severity 041 ndash 065 009 065

Age ndash011 009 030 002 030

Disease severity (PASI) 015 020 021 ndash036 033

Disease duration (years) ndash007 001 003 ndash014 007

Average hours of sleep ndash022 ndash029 ndash026 ndash016 ndash023

Total Impairment of Sleep 016 059 064 021 062

Depressive symptoms (BDI-13) 034 049 048 014 041

Distress Global Severity Index (BSI-18) 039 049 039 ndash008 047

Pruritus-related Quality-of-Life (DLQI) b 015 052 058 002 060

aPartial correlation controlling for perceived severity of mosquito bite bModied DLQI omitting irrelevant items and item relating directly to perceived itch and phrasing items to relate to impairment of quality of life due

to itch

p lt 005 p lt 001VAS visual analogue scale PASI Psoriasis Area and Severity Index BDI-13 short 13-item version of Beck Depression Inventory BSI-18 18-item Brief

Symptom Inventory DLQI Dermatology Life Quality Index R correlation coefcient





scores and when controlling for this variable VAS pruritus severity was signicantly positively correlatedwith PASI scores APS scores showed several moderateto large correlations while SPS showed fewer and moremoderate correlations When analysing the independent

contribution of APS and SPS to VAS pruritus severitywith multiple linear regression only APS was a signi-cant predictor (beta 064 p lt 0001) while SPS wasnot (beta 004 p = 079)

Multiple hierarchical linear regression analyses wereconducted with depressive symptoms global severity

of distress scores and impairment of QoL as indepen-dent variables and age sex disease duration diseaseseverity APS SPS and sleep impairment as independentvariables with sleep impairment entered at the secondand last step The results are shown in Table III At therst step only APS was signicantly associated with

depressive symptoms and ceased to be signicant whensleep impairment was entered at the second step Age

and APS were signicant predictors of global severityof distress at the rst step and only age after enteringsleep impairment into the equation For QoL impair-ment APS continued to be a signicant predictor afteradding sleep impairment to the model Neither disease

severity nor SPS were signicantly associated with theindependent variables Similar results were found whenanalysing the associations with depression and distresscaseness as categorical variables with multiple hierar-chical logistic regression analyses with APS being theonly signicant predictor of moderate-severe depression

and distress caseness (data not shown)

When entering sleep impairment into the equationsthe associations between APS and depression and dist-ress ceased to be signicant suggesting that sleep impairment could be a mediator of the negative inuenceof APS on depression and distress A further analysis of

mediation was therefore conducted for impaired sleepquality as a mediator of the association between APSand the dependent variables of depressive symptomsglobal severity of distress scores and impairment ofQoL As seen in Table IV when applying the criteria formediation both tests revealed impairment of sleep qua-

lity to be a partial mediator of the association betweenAPS and global severity of distress Although the directtest only yielded a near-signicant ( p = 007) result theresults indicated that impairment of sleep quality wasalso a partial mediator of the association between APSand depressive symptoms In contrast the results for the

association between APS and impairment of QoL didnot show impairment of sleep quality to be a mediatorof this association

DISCUSSION

Itch is a complex subjective phenomenon a factorgenerally not addressed in previous studies of pruritus

focusing only on the intensity of itch eg with single

items or using single VAS Our results conrm that the patientsrsquo perception of pruritus and its severity likethe phenomenon of pain is multidimensional Whenanalysing the 10 pruritus descriptors proposed byYosipovitch et al (12) with an exploratory factoranalysis our results conrmed 2 distinct dimensions

One dimension consisted of 4 of the 6 descriptorsrepresenting the sensory dimension of pruritusnamely ldquocrawling like antsrdquo ldquoticklingrdquo ldquopinchingrdquoand ldquostabbingrdquo The second dimension included all4 descriptors labelled as affective ie ldquounbearablerdquo

Table III Results of multiple hierarchical linear regressions withdepressive symptoms global severity of distress and impairmentof quality of life (QoL) as dependent variables and demographicsdisease characteristics and severity of pruritus as independentvariables

Dependent variable Beta p R2

Depressive symptoms (BDI-13) predictors

Step 1 Age 024 ns

Sex 008 nsDisease duration 016 ns

Disease severity (PASI) ndash011 ns

Sensory Pruritus Severity 012 ns

Affective pruritus Severity 046 001 032

Step 2 Age ndash021 ns

Sex 007 ns

Disease duration 013 ns


Sensory pruritus severity 015 ns

Affective pruritus severity 029 ns

Total sleep quality 028 ns 037

Distress (BSI-18) predictors

Step 1 Age ndash033 005




Affective pruritus severity 052 0001 037


Sex 016 ns






Pruritus-related QoL (DLQI )


Sex 000 ns


Disease severity (PASI) 008 ns




Sex ndash001 ns




Affective pruritus severity 050 001


PASI Psoriasis Area and Severity Index BDI-13 short 13-item version of

Beck Depression Inventory BSI-18 18-item Brief Symptom Inventory

DLQI Dermatology Life Quality Index ns not signicant





ldquoworrisomerdquo bothersomerdquo and ldquoannoyingrdquo Two of theoriginal sensory descriptors ldquoburningrdquo and ldquostingingrdquohowever loaded on a separate dimension togetherwith the 4 affective descriptors In addition these 2descriptors were signicantly associated with depres-

sive symptoms and global distress while the remainingsensory descriptors were not Taken together this couldsuggest that ldquoburningrdquo and ldquostingingrdquo or at least in theirDanish translations (ldquobraeligndenderdquo and ldquo svienderdquo) are

not perceived by patients as purely sensory but have anaffective connotation The results indicate that furtheranalyses are needed in larger patient samples with

different linguistic and cultural backgrounds if we areto identify valid descriptors of the sensory and affectivedimensions of pruritus

Another aim of the study was to investigate the pos-sible associations between the different dimensionsof pruritus and psychological symptoms A large

proportion of the patients in this sample showed signi-cant depressive symptoms (30) and global distress(425) supporting previous ndings of psychological

co-morbidity in patients with pruritus (4) and in psoria-sis and other dermatological patients in general (30)When exploring the univariate correlations between the

severity of affective and sensory pruritus and impair-ment of sleep depressive symptoms global distress andimpairment of QoL affective pruritus severity showedlarger and more consistent correlations than sensory pruritus severity suggesting that the affective dimensionis more important than the sensory even though the 2

dimensions correlated moderately with each other Thiswas conrmed in the multivariate analyses verifyingaffective and not sensory pruritus severity as the main predictor of psychological symptomatology It should be noted that neither intensity of pruritus as measured

on a VAS nor the affective or sensory severity di-mensions of pruritus were found to be associated withdermatology-rated disease severity as assessed by thePASI This nding is consistent with results reported by Yosipovitch et al (1) In addition no associations

were found between PASI scores and all 3 dependentvariables of depressive symptoms global distress andimpairment of QoL This is in concordance with pre-vious results from a study of Nordic psoriasis patients

showing that while self-reported disease severity wasa signicant predictor PASI scores were unrelated toimpairment of psoriasis-related QoL (31) The results

underscore the necessity to assess patientsrsquo perceptionsof different aspects of their disease For comparison ameasure of the perceived severity of a mosquito bite wasincluded and mean intensity of pruritus as measuredon the VAS was signicantly greater than the meanscores on this comparison measure The comparison

measure did not correlate with affective or sensory pruritus severity and the only statistically signicantcorrelation found for perceived severity of a mosquito

bite was an inverse correlation with PASI scores Wehave no clear explanation for this result One possibleexplanation could be that psoriasis may reduce the

sensitivity to other sensory stimuli This explanation issupported by recent results showing reduced sensitivityto histamine prick tests in both lesional and non-lesionalskin of psoriasis patients compared with higher sensiti-vity in lesional skin of atopic dermatitis patients (32)Another explanation could be that more severe disease

could inuence the interpretation of minor annoyancessuch as a mosquito bites making them relatively lessimportant to the patient

Psoriasis patients report that their itch becomes worseat night but is ameliorated by sleep (1) and a large

Table IV Results of analyses of impairment of sleep quality as a mediator of the association between affective pruritus severity and thedependent variables of depressive symptoms global severity of distress and impairment of quality of life (QoL)

Step Coefcient p

Testing for mediation of the association between affective pruritus severity and depressive symptoms (BDI-13)

A IV predicts DV 063 0001

B IV predicts mediator 026 00001

C Mediator predicts DV controlling for the IV 098 005

D IV-DV association reduced controlling for the mediator 037 009

Sobel direct test of mediation effect 026 p = 007Testing for mediation of the association between affective pruritus severity and global severity of distress (BSI-18)





Sobel direct test of mediation effect 059 p = 004

Testing for mediation of the association between affective pruritus severity and impairment of QoL (DLQI-modied)






IV independent variable DV dependent variable BDI-13 short 13-item version of Beck Depression Inventory BSI-18 18-item Brief Symptom

Inventory DLQI Dermatology Life Quality Index





proportion of atopic dermatitis patients with pruritusreport difculties falling asleep (16) Depressed patientsoften report sleep problems including difculties fal-ling and staying asleep as well as poor subjective sleepquality ndings that have been conrmed by objective

assessments through polysomnography (17 33) Wetherefore wished to investigate whether the association between pruritus severity and psychological symptomsand impairment of quality of life was mediated by impairment of sleep quality Using the statistical approachto test mediation suggested by Baron amp Kenny (27) and

Kenny et al (29) our results suggested that impairedsleep quality partly mediated the association betweenaffective pruritus severity and depressive symptomsand global distress Our ndings differ from those ofan earlier study where pruritus severity did not differ between psoriasis patients with and without nocturnal

wakening (34) The different results could stem from thedifferences in pruritus and sleep quality measurements

used in the 2 studies and further studies are needed toexplore the associations between pruritus sleep qualityand psychological symptoms We did not nd sleepquality to mediate the association with QoL where theassociation with pruritus severity continued to be statis-

tically signicant when controlling for sleep quality TheQoL measure assessed the negative inuence of prurituson social relations work and other daily activities Thiscould explain the result as these factors are less likelyto be inuenced by sleep difculties than psychologicalsymptoms Although the modied DLQI showed good

internal consistency and the correlations with pruritus

severity could be interpreted as an indicator of its vali-dity as a measure of pruritus-related QoL-impairmentthe reliability and validity of the measure clearly needsto be explored further The relatively modest samplesize (n = 40) should also be taken into consideration

Taken together alleviating sleep problems may thus bea potentially benecial avenue to take when attemptingto reduce the negative impact on psychological well- being of patients with pruritus

Our results conrm previous ndings of psycho-logical co-morbidity in patients with pruritus Taken

together our results also indicated that pruritus in particular the affective dimension was a signicantcontributor to these symptoms an association thatwas at least partly mediated by impaired sleep qualityThe results highlight the necessity to assess patientsrsquo perceptions of different aspects of their disease and to

continue the development of reliable valid measuresof these aspects

ACKNOWLEDGEMENT

The study was supported by Astion Pharma Ltd Denmark

REFERENCES

1 Yosipovitch G Goon A Wee J Chan YH Goh CL The prevalence and clinical characteristics of pruritus among patients with extensive psoriasis Br J Dermatol 2000 143969ndash973

2 Buske-Kirschbaum A Geiben A Hellhammer D Psy-chobiological aspects of atopic dermatitis an overviewPsychother Psychosom 2001 70 6ndash16

3 Kosmadakis GC Zerefos N Uremic pruritus Int J ArtifOrgans 2006 29 938ndash9434 Schneider G Driesch G Heuft G Evers S Luger TA

Stander S Psychosomatic cofactors and psychiatriccomorbidity in patients with chronic itch Clin Exp Dermatol2006 31 762ndash767

5 Gupta MA Somatization disorders in dermatology Int RevPsychiatry 2006 18 41ndash47

6 Niemeier V Kupfer D Gieler U Observations during an itch-inducing lecture Dermatol Psychosom 1991 1 15ndash19

7 Dark K Peeke HV Ellman G Sal M Behaviorally condi-tioned histamine release Prior stress and conditionabilityand extinction of the response Ann N Y Acad Sci 1987496 578ndash582

8 Zachariae R Bjerring P Arendt-Nielsen L Modulation oftype I immediate and type IV delayed immunoreactivityusing direct suggestion and guided imagery during hypno-sis Allergy 1989 44 537ndash542

9 Zachariae R Joslashrgensen MM Egekvist H Bjerring P Skinreactions to histamine of healthy subjects after hypnoticallyinduced emotions of sadness anger and happiness Allergy2001 56 734ndash740

10 Zachariae R Bjerring P The effect of hypnotically inducedanalgesia on are reaction of the cutaneous histamine pricktest Arch Dermatol Res 1990 282 539ndash543

11 Gupta MA Gupta AK Kirkby S Weiner HK Mace TMSchork NJ et al Pruritus in psoriasis A prospective studyof some psychiatric and dermatologic correlates Arch

Dermatol 1988 124 1052ndash105712 Yosipovitch G Zucker I Boner G Gafter U Shapira Y DavidM A questionnaire for the assessment of pruritus validationin uremic patients Acta Derm Venereol 2001 81 108ndash111

13 Ikoma A Steinhoff M Stander S Yosipovitch G SchmelzM The neurobiology of itch Nat Rev Neurosci 2006 7535ndash547

14 Holroyd KA Talbot F Holm JE Pingel JD Lake AESaper JR Assessing the dimensions of pain a multitrait-multimethod evaluation of seven measures Pain 1996 67259ndash265

15 Melzack R The McGill Pain Questionnaire major proper-ties and scoring methods Pain 1975 1 277ndash299

16 Yosipovitch G Goon AT Wee J Chan YH Zucker I Goh

CL Itch characteristics in Chinese patients with atopicdermatitis using a new questionnaire for the assessment of pruritus Int J Dermatol 2002 41 212ndash216

17 Tsuno N Besset A Ritchie K Sleep and depression J ClinPsychiatry 2005 66 1254ndash1269

18 Buysse DJ Reynolds CF Monk TH Berman SR KupferDJ The Pittsburg Sleep Quality Index A new instrumentfor psychiatric practice and research Psychiatry-Research1989 28 193ndash213

19 Beck AT Beck RW Screening depressed patients in family practice A rapid technique Postgrad Med 1972 52 81ndash85

20 Love AW Grabsch B Clarke DM Bloch S Kissane DWScreening for depression in women with metastatic breastcancer a comparison of the Beck Depression Inventory





Short Form and the Hospital Anxiety and Depression ScaleAust N Z J Psychiatry 2004 38 526ndash531

21 Zachariae R Christensen S Joslashrgensen MM Jensen ABRavnsbaeligk J Moslashller S et al Alexithymia in 3486 womentreated for breast cancer ndash associations with distress Psy-chosom Med 2005 67 A33

22 Zabora J BrintzenhofeSzoc K Jacobsen P Curbow BPiantadosi S Hooker C et al A new psychosocial screeninginstrument for use with cancer patients Psychosomatics

2001 42 241ndash24623 Finlay AY Khan GK Dermatology Life Quality Index(DLQI) ndash a simple practical measure for routine clinicaluse Clin Exp Dermatol 1994 19 210ndash216

24 Zachariae R Zachariae C Ibsen H Mortensen JT Wulf HCDermatology life quality index data from Danish inpatientsand outpatients Acta Derm Venereol 2000 80 272ndash276

25 Frederiksson T Pettersson U Severe psoriasis oral therapywith a new retinoid Dermatologica 1978 157 238ndash244

26 Abdi H Bonferroni and Sidak corrections for multiplecomparisons In Salkind NJ editor Encyclopedia of mea-surement and statistics Thousand Oaks CA Sage 2007

27 Baron RM Kenny DA The moderator-mediator variabledistinction in social psychological research conceptual

strategic and statistical considerations J Pers Soc Psychol1986 51 1173ndash1182

28 Preacher KJ Hayes AF SPSS and SAS procedures for esti-mating indirect effects in simple mediation models BehavRes Methods Instrum Comput 2004 36 717ndash731

29 Kenny DA Kashy DA Bolger N Data analysis in social psychology In Gilbert D Fiske S Lindzey G editors Thehandbook of social psychology Boston MA McGraw-Hill1998 p 233ndash265

30 Zachariae R Zachariae C Ibsen H Mortensen JT Wulf HCPsychological symptoms and quality of life in dermatology

outpatients and hospitalized dermatology patients ActaDerm Venereol 2004 84 205ndash21231 Zachariae R Zachariae H Blomqvist K Davidsson S Molin

L Mork C et al Quality of life in 6497 Nordic patientswith psoriasis Br J Dermatol 2002 146 1006ndash1016

32 Ikoma A Rukwied R Stander S Steinhoff M Miyachi YSchmelz M Neuronal sensitization for histamine-induceditch in lesional skin of patients with atopic dermatitis ArchDermatol 2003 139 1455ndash1458

33 Argyropoulos SV Wilson SJ Sleep disturbances in depres-sion and the effects of antidepressants Int Rev Psychiatry2005 17 237ndash245

34 Gupta MA Gupta AK Kirkby S Schork NJ Weiner HKEllis CN et al Pruritus associated with nocturnal wa-

kenings organic or psychogenic J Am Acad Dermatol1989 21 479ndash484





on different aspects of QoL All of the patients agreed to parti-cipate and completed a questionnaire package The study wasconducted in accordance with the requirements of the localethics committee

Measures

bull A Pruritus Severity Questionnaire listing the 6 sensory descrip-tors (ldquocrawling like antsrdquo ldquoticklingrdquo ldquopinchingrdquo ldquostabbingrdquoldquostingingrdquo and ldquoburningrdquo) and 4 affective descriptors (ldquoun-

bearablerdquo ldquoworrisomerdquo bothersomerdquo and ldquoannoyingrdquo) asdescribed by Yosipovitch et al (12) Each descriptor wasranked on a 4-point Likert scale from 0 = none to 3 = severeTwo independent translations into Danish of the Englishdescriptors were discussed and a preliminary version wasagreed upon This version was back-translated and a finalversion was prepared taking any discrepancies between the2 versions into consideration

bull Severity of pruritus was also assessed on a 100-mm visualanalogue scale (VAS) with end-points anchored by ldquono itchrdquoand ldquoas bad as could possibly berdquo As a comparison measurethe patients were also asked to rate on a VAS the severity ofthe strongest itch after a mosquito bite

bull A short Sleep Quality Questionnaire consisting of 3 modifieditems from the Pittsburg Sleep Quality Index (18) The pa-tients were asked to rate on a 4-point scale (i) how much their

pruri tus had made it difficult to sleep during the past week(ii) how well they had generally slept during the past week(reversely scored) and (iii) whether they had used any sleepmedication during the past week A total Impairment of Sleepscore (0ndash9) was calculated by adding the scores of the 3 itemswith higher scores indicating greater impairment of sleep The

patients were also asked to estimate the average number ofhours they had slept per night during the past week

bull The short 13-item version of Beck Depression Inventory (BDI-13) (19) The short version has been shown to be a reliableand valid screening instrument for depression (20) Tested in a

sample of 3486 Danish women treated for breast cancer (21)the BDI-13 has shown good internal consistency (Cronbachrsquosalpha 083) and validity Scores for each item range from 0to 3 yielding a total depression score ranging from 0 to 39Receiver operating characteristic (ROC) analysis using thesame sample showed that a cut-off of 9 yielded both highsensitivity (986) and specificity (946) for identifying

participants characterized as having moderate-severe depres-sion on the full 21-item BDI

bull The 18-item Brief Symptom Inventory (BSI-18) (22) was usedfor assessing general distress Scores on each item rangesfrom 0 to 4 and a Global Severity Index is calculated withscores ranging from 0 to 72 The suggested cut-off scores fordistress caseness of 10 for men and 13 for women (22) were

used to identify patients with high vs low distressbull To measure QoL impairment directly related to the impact of pruri tus we modified the Dermatology Life Quality Index(DLQI) (23 24) Item 1 referring directly to pain or itchseverity was excluded as this otherwise would artificiallyincrease the association with the pruritus severity measureinvestigated Item 2 which refers to embarrassment due toappearance was excluded together with item 10 which refersto problems related to the treatment of the skin condition asthese items are unrelated to pruritus The remaining itemswere rephrased to refer directly to difficulties due to pruritusReliability was tested in the present sample

bull Questions concerning age disease duration co-morbidityand medication

bull Finally psoriasis severity was assessed by a dermatologistusing the Psoriasis Area and Severity Index (PASI) (25)

Statistical analysis

The dimensional structure of the pruritus descriptors was ana-lysed with an exploratory principal components analysis withvarimax rotation Variables were plotted inspected and testedfor normality BDI-13 and BSI-18 scores were skewed anddeviated significantly from normality (Kolmogorov-Smirnovtest) The variables were successfully transformed using thesquare root (BDI-13) and log-10 (BSI-18) The data for menand women were compared with χ2 tests and t -tests for inde-

pendent samples correcting for multiple comparisons with theBonferroni method (26) Correlations between variables werecalculated and the influence of the 2 different dimensions of

pruritus on depressive symptoms general distress and QoL wasanalysed with multiple hierarchical linear regression analysescontrolling for age sex disease duration disease severity andsleep quality In addition logistic regression was used to test theassociations between pruritus and the risk of being classified ashaving moderate-severe depression as well as general distresscaseness Finally the possible mediating effects of sleep qualityon these associations were explored Baron amp Kenny (27) andKenny et al (29) have defined 4 analytical steps necessary toestablish mediation (i) the independent variable (IV) should bea significant predictor of the dependent variable (DV) (ii) the

IV should predict the mediator (iii) the mediator should predictthe DV when controlling for the IV and (iv) the association

between the IV and the DV should be reduced when controllingfor the mediator Complete mediation of the IVndashDV associationrequires that the IVndashDV association is reduced to zero whencontrolling for the mediator Partial mediation requires the as-sociation to be reduced to a non-trivial size but not to zero Inaddition for each of the 3 DVs the Sobel test was used as adirect test of mediation (28)

RESULTS

Cronbachrsquos alpha of the BDI-13 BSI-18 and the mo-died DLQI were 090 092 and 085 respectivelyindicating good internal consistency in the presentsample The demographic characteristics of the patient

sample including sex age disease severity (PASI)and disease duration are shown in Table I The scoreson the 10 pruritus severity descriptors were analysedwith an exploratory principal components analysis withvarimax rotation The rotation converged in 3 iterationsand conrmed 2 distinct independent factors Factor

1 termed the affective dimension consisted of the 4original affective descriptors described by Yosipovitch

et al (12) ie ldquounbearablerdquo ldquoworrisomerdquo bothersomerdquoand ldquoannoyingrdquo together with 2 of the original sensorydescriptors ldquoburningrdquo and ldquostingingrdquo Factor 2 thesensory dimension consisted of the 4 sensory descrip-tors of ldquocrawling like antsrdquo ldquoticklingrdquo ldquopinchingrdquo

and ldquostabbingrdquo When analysing the non-parametriccorrelations between the scores of each descriptorwith total BDI-13 and BSI-18 scores the originalsensory descriptors of ldquoburningrdquo and ldquostingingrdquo weresignicantly associated with both depressive symptoms(rho 046ndash047 p lt 001) and distress (rho 053ndash055

p lt 001) while the remaining sensory descriptors werenot (rho 010ndash030 ns)















Men

(n = 24)

Women

(n = 16) p b Total

Age (years) 507 (131) 585 (125) 007 538 (133)



Co-morbidity () 550 450 052 500













Life Quality Index


R

Sensory Pruritus

Severity (SPS)

Affective Pruritus

Severity (APS)

Pruritus severity 1

(VAS)

Perceived

severity of

mosquito bite

(VAS)

Pruritus severity 2

(VAS)a




Age ndash011 009 030 002 030









to itch



















DISCUSSION








Step 1 Age 024 ns






Sex 007 ns













Sex 016 ns








Sex 000 ns






Sex ndash001 ns
































Step Coefcient p




































ACKNOWLEDGEMENT


REFERENCES


























































Men

(n = 24)

Women

(n = 16) p b Total

Age (years) 507 (131) 585 (125) 007 538 (133)



Co-morbidity () 550 450 052 500













Life Quality Index


R

Sensory Pruritus

Severity (SPS)

Affective Pruritus

Severity (APS)

Pruritus severity 1

(VAS)

Perceived

severity of

mosquito bite

(VAS)

Pruritus severity 2

(VAS)a




Age ndash011 009 030 002 030









to itch



















DISCUSSION








Step 1 Age 024 ns






Sex 007 ns













Sex 016 ns








Sex 000 ns






Sex ndash001 ns
































Step Coefcient p




































ACKNOWLEDGEMENT


REFERENCES




























































DISCUSSION








Step 1 Age 024 ns






Sex 007 ns













Sex 016 ns








Sex 000 ns






Sex ndash001 ns
































Step Coefcient p




































ACKNOWLEDGEMENT


REFERENCES



































































Step Coefcient p




































ACKNOWLEDGEMENT


REFERENCES




























































ACKNOWLEDGEMENT


REFERENCES












































affective and sensory dimensions of pruritus severity

Documents