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Quality of life (QoL) for patients with inflammatory skin disease can be significant, but has been evaluated in just one study in dermatomyositis (DM).
To examine the relationship between the Cutaneous Disease and Activity Severity Index (CDASI), a DM-specific cutaneous severity instrument, and various QoL study instruments and to determine the impact of DM on QoL.
Skin-specific QoL instruments, the Skindex and the Dermatology Life Quality Index (DLQI), and global medical QoL instruments, the SF-36 and the HAQ-DI, were used. Pruritus was evaluated by a visual analogue scale (VAS) and a 0–10 scale in DM and CLE populations, respectively.
There was a significant correlation between the CDASI and all skin-specific QoL scores (lowest p=0.0377). Using the SF-36, DM was found to have significantly worse QoL scores than the general population with the exception of bodily pain (all subscore p values <0.01). Furthermore, DM had a significantly lower vitality score, representing energy level, compared to CLE, HTN, diabetes, and recent MI scores (lowest p=0.003). There was a significantly lower mental health score, representing overall mood, to all compared diseases except CLE and clinical depression (p values < 0.01 when significant). We found that DM produces more pruritus than CLE (p < 0.0001).
A larger patient population needs to be studied to further assess QoL in DM patients.
We conclude that DM has a large impact on QoL, even when compared to other diseases, and that DM skin disease activity correlates with a poorer QoL.
Dermatomyositis (DM) belongs to a group of diseases called idiopathic inflammatory myopathies1. Patients with amyopathic and hypomyopathic dermatomyositis demonstrate absent or clinically insignificant muscle findings2. Recently, a tool called the Cutaneous Dermatomyositis Area and Severity Index (CDASI) was validated as a useful means to measure cutaneous findings in dermatomyositis quantitatively3, 4.
Cutaneous autoimmune diseases have a negative impact on quality of life (QoL) 5,6–8. Up to now, there has been only one published report on the impact of DM on a patient’s QoL9. Now that new skin evaluation instruments and comparable data between DM and other diseases are available, studies on QoL in DM can be introduced into the literature.
Recently we performed a prospective study on a cohort of DM patients with skin involvement using the CDASI to elucidate the impact of the disease on their QoL and to demonstrate the need for more effective therapies that may include the use of off-label medications when standard less expensive options are ineffective. A substantial percentage of DM patients have psychiatric disease, especially depression and anxiety, compared to the normal population, the prevalence ranging from approximately 20–40% of DM patients, compared to 11–30% of normal persons, respectively10–17. Only one study has examined patients with cutaneous DM using a 5-point Physician’s Global Assessment and skin-specific QoL measures9. No studies on DM have been performed using global health QoL measures. DM is a systemic disease, and thus it is important to study its effects on QoL using global medical QoL measures in addition to dermatologic QoL measures.
Comparing the QoL in DM relative to other dermatologic and non-dermatologic diseases is important in order to evaluate more completely its impact on QoL. Our previous work with a large cohort of cutaneous lupus patients showed that lupus patients have a significantly lower QoL than patients with common skin diseases such as non-melanoma skin cancer, acne, and alopecia5. Cutaneous lupus erythematosus had a greater effect on QoL relative to non-dermatologic diseases such as hypertension, type II diabetes mellitus, congestive heart failure, and recent myocardial infarction. There was no significant difference between lupus and DM using the Skindex-29 in a DM group5. Further research into comparisons of QoL between patients with DM and patients with cutaneous lupus is needed.
Our study examined the importance of clinical signs or symptoms in DM relative to cutaneous lupus to aid in assessing therapeutic efficacy. Pruritus, for example, is a common symptom experienced by many DM patients18. While it has been suggested that pruritus can be used as a distinguishing marker between DM and cutaneous lupus, it is also a prevalent symptom in both juvenile and adult DM. There have not been any studies showing a difference between the pruritus experienced by patients with DM and patients with cutaneous lupus patients19–21.
All patients with clinical or pathologic evidence of DM seen at the Hospital of the University of Pennsylvania and Stanford University dermatology clinics were invited to participate in the study regardless of whether or not they were currently undergoing treatment. 55 patients from the University of Pennsylvania and 65 patients from Stanford University were enrolled in the study. Of the 42 patients from the University of Pennsylvania who were able to participate in a study visit, 42 patients had their skin assessed by the CDASI, 42 completed the DLQI, 41 completed the Skindex 29+3, 40 completed the Pain VAS, 40 completed the Itch VAS, 40 completed the Patient Global Assessment, 42 completed the SF-36, and 39 patients completed the HAQ. Of the 42 patients from the University of Pennsylvania, 8 patients were male, 34 patients were female, 14 had classic DM with active muscle involvement, and 28 had no active muscle involvement. Of the 55 patients from Stanford University who were able to participate in a study visit, 55 had their skin assessed by the CDASI, 50 patients completed the HAQ, 50 patients completed the DLQI, 50 patients completed the Pain VAS, 49 patients completed the Itch VAS, and 7 patients completed the SF-36 fully (10 patients completed all but the Role-Emotional aspect of the SF-36). The differences in the number of completed questionnaires are due to non-completion of the study questionnaires by error by the study subjects. The large discrepancy in Stanford’s population completing the SF-36 is due to their later introduction of the SF-36 into the study documents for their subjects. There was no selection bias to which patients ultimately completed or did not complete the questionnaires. Of the 55 patients from Stanford University, 15 were male and 40 were female. The subtype of DM was not recorded in the Stanford population at the time of the research visit.
194 patients seen at the Hospital of the University of Pennsylvania dermatology clinic with clinical and/or pathological evidence of lupus were invited to participate in the study. Of these, 123 patients had CLE without systemic involvement and 71 patients had SLE with cutaneous disease. 178 of the 194 patients with lupus completed the Skindex 29. 161 and 162 patients completed the pruritus and pain assessment scales, respectively. Of the 123 CLE patients, 112 patients completed the SF-36 and 65 of the 71 SLE patients completed the SF-36. The study was approved by the institutional review board (IRB). All patients were age 18 or above and were enrolled after signing IRB-approved informed consent and Health Insurance Portability and Accountability Act (HIPAA) forms.
A number of study instruments were completed at the same visit. To assess QoL among DM patients, two skin-specific QoL measures, the Skindex-29+3 and the Dermatology Life Quality Index (DLQI), and two global health QoL measures, the Short Form 36 (SF-36) and the Health Assessment Questionnaire-Disability Index (HAQ-DI), were completed by patients. Additionally, patients answered questions regarding their demographics and disease history. To assess disease severity, the physician completed the CDASI and physician global assessment measures.
The Skindex-29 is a validated skin-specific measure of QoL 22–243, 25. Each question has 5 choices, scored as 100, 75, 50, 25, or 0. Scoring is categorized to different subscales. These include functioning, symptoms, emotions, and photosensitivity. Three questions were added to represent DM-specific effects: namely two questions for photosensitivity and one question for alopecia. The maximum score in each category is 100, indicating maximum disability.
The DLQI was the first validated dermatologic QoL study instrument to be described826. It measures the effect of dermatologic disease on QOL and consists of 10 questions, each of which can be answered by marking one of four choices. These are scored from 0–3, with a maximum total score of 30, indicating maximum disability. The DLQI has been previously shown to be reliable and valid8, 26.
The SF-36 is a global medical QOL study instrument that previously has been shown to be reliable and valid27, 28. The instrument consists of 36 items answered by marking from 2–6 options. Scoring ranges from 0–100, with zero indicating maximum disability. Scores are categorized to the following: physical functioning (PF), role-physical (RP), bodily pain (BP), general health (GH), vitality (VT), social functioning (SF), role-emotional (RE), and mental health (MH) (See Table 1). The first four scores can be summed to create the physical composite score (PCS), while the last four can be summed to create the mental composite score (MCS). The SF-36 was used to compare QoL with DM to lupus, congestive heart failure (CHF), recent myocardial infarction (MI), depression, and hypertension (HTN) using the SF-36 Health Survey and values obtained from our previous work, except for SLE and CLE values, which were obtained during this study29.
The HAQ-DI is a global medical study instrument found to be reliable and valid30–32. The combined responses to questions indicating the difficulty in performing 20 different instrumental activities assess the level of disability of the patient. Each is scored from 0–3, with 3 representing maximum disability. The HAQ-DI consists of 24 questions which assess eight instrumental activities:(1) Dressing and Grooming, (2) Arising, (3) Eating, (4) Walking, (5) Hygeine, (6) Reach, (7) Grip, and (8) Activities.
The CDASI, a validated disease severity score, was used to determine the severity of cutaneous disease. Total scores range from 0–132, which are divided into (1) Activity and (2) Damage, with scores ranging from 0–100 and 0–32, respectively.
Pruritus and pain were measured using a visual analogue scale (VAS). For pruritus, the VAS has been used extensively and has been found to be useful in a clinical research setting25, 33, 34. The VAS has been known to be a ‘gold standard’ for assessing pain35–38. The VAS is a 100 mm horizontal line with one end representing maximum itch or pain and the other expressing no itch or pain. Lupus patients used a 0–10 scale to represent the amount of pruritus and pain with 10 indicating maximum itch or pain and 0 indicating no itch or pain.
The physician and patients were asked to rate the severity of various aspects and overall disease of DM using a VAS from 0–10, where 10 indicates maximum severity.
Descriptive statistics were obtained for each of the QoL measures for the DM population. Using the Skindex-29, mean DM scores (one score for each of the three subscales) were compared to mean scores of other dermatologic diseases obtained through literature review, our lab results for CLE, or from data obtained from Chren MM39–42. Using the SF-36, mean DM norm-based scores (one score for each of the eight subscores) were compared to those of seven other diseases and the general population norm-based scores. SLE and CLE data was obtained from our lab while other compared diseases were obtained from a previous paper evaluating QoL in CLE5. Since standard deviations were not available for compared groups other than SLE or CLE, it was assumed that the standard deviation of DM was non-significantly different from other groups (SLE and CLE standard deviations were used since they were available). Skindex 29 and SF-36 means were compared by using a two-tailed t-test at an adjusted significance level of 0.01. Mean HAQ-DI and SF-36 subscores were compared between classic dermatomyositis (CDM) and amyopathic or hypomyopathic dermatomyositis (AHDM) using the Mann- Whitney U test at an adjusted significance level of 0.01. The adjusted significance level was used to minimize experiment-wise error rate. Mean itch, pain, and photosensitivity scores for CLE and DM were compared using the Mann-Whitney U test at a significance level of 0.05. To determine the correlation between disease severity and QoL, CDASI activity scores were correlated with the Skindex-29 and the DLQI, using Pearson’s correlation. Since there is no straightforward mean to test the difference between two Spearman’s rho, Pearson’s correlation was used to determine the correlation between SF-36 subscores and HAQ-DI scores to the Patient Global Assessment-Overall Disease and the Skindex-Emotion. To determine the significance of statistical differences among correlated correlations, we used the Z test43. Non-parametric tests were used due to the non-normality of certain variables.
DM was found to have a mean (SD) DLQI score of 7.6 (6.5) and a HAQ-DI score of 0.795 (0.788). Each of the Skindex-29 and SF-36 subscores, pruritus, and pain score will be described below and in corresponding tables. The mean (SD) CDASI activity score in our study population was 19.5 (10.5). All of the outcome measures had a mixed distribution except for the HAQ, which had a positively-skewed distribution.
The Skindex-29 subscores were used to compare DM with 12 other dermatologic diseases and one negative control group (See Table 1). DM had among the highest mean subscores, with the emotional subscore being the most severely affected [mean (SD) = 50.4 (26.1)]. The emotional subscore in DM was significantly higher than in epidermolysis bullosa, pemphigus, CTCL, rosacea, non-melanoma skin cancer/actinic keratoses (NMSC/AK), vitiligo, and the negative control group. DM hadthe highest emotional subscore among all compared groups with the exception of vulvodynia, which had an approximately equivalent emotional subscore. DM also showed a higher mean symptom subscore than all compared groups except for vulvodynia, epidermolysis bullosa (mixture of various subtypes), and eczema, and had a significantly higher score compared to acne vulgaris, CTCL, NMSC/AK, vitiligo, and normal skin. DM patients were less severely affected in the functional realm with a mean (SD) score of 28.2 (26.6), significantly lower than vulvodynia but significantly higher than NMSC/AK, vitiligo, and normal skin.
The SF-36 subscores were used to compare DM with seven other diseases and the general population (See Table 2). When compared to the general population, DM was found to have significantly poorer scores in all domains, except for bodily pain. In the physical realm, DM was found to have significantly poorer scores than CLE, type II diabetes, clinical depression, and hypertension, and a significantly better score than SLE either in some or all of the physical domains. DM had the poorest score in physical functioning with a mean (SD) of 39.6 (14.85). In the social/emotional realm, DM had significantly worse score(s) to CHF, recent MI, type II diabetes, and hypertension, though a significantly better score to clinical depression. DM had the poorest score in role-emotional with a mean (SD) of 42.6 (13.71).
HAQ-DI and SF-36 scores were used to compare classic DM with hypomyopathic/ amyopathic DM. Although mean scores in the physical subscores of the SF-36 and the HAQ-DI suggest poorer QoL in the classic DM population, statistical significance was not reached (Table 3).
DM was found to have a significantly higher median pruritus score than CLE (DM: 3.80 CLE: 2) (p<0.0001) whereas there was no significant difference between median pain scores (DM: 0.7 CLE: 1). Figure 1 gives graphical representations of both findings.
Median scores from the two photosensitivity questions added to the Skindex-29 showed no significant difference between DM and CLE (DM: 62.5 CLE: 62.5) (Figure 2).
Each of the Skindex-29 subscores significantly correlated with the DLQI scores (Skindex-29 Symptom r=0.6323, Skindex-29 Emotion r=0.6744, Skindex-29 Function r=0.8598; all p values<0.0001), implying that the DLQI and the Skindex-29 measure related constructs. The Skindex-29 scores were also found to correlate with one another (lowest r=0.5345, highest p=0.0003) (Table 4). Additionally, the correlation between DLQI and Skindex-29 Function scores were significantly higher than the correlation between DLQI and Skindex-29 Emotion scores (p=0.004).
All of the Skindex-29 subscores and the DLQI scores significantly correlated with CDASI scores (r=0.2729, p=0.0377), suggesting that increased cutaneous severity is correlated with a poorer QoL (Table 5). .
Pruritus scores correlated significantly with Skindex-Symptom, Skindex-Function and DLQI scores (r=0.6015 p=0.001; r=0.45520 p=0.0036; r=0.3477 p=0.0009, respectively), but significance was not attained between pruritus and Skindex-Emotion subscores. The above results implicate that pruritus is associated with a poorer QoL, though it may not significantly affect a patient emotionally (Table 5).
The correlations between each of the physical component SF-36 subscores and the HAQ-DI scores to the overall patient global assessment (PtGA) were determined. Additionally, the correlations between each of the emotional component subscores and the HAQ-DI scores to the Skindex-Emotion score were determined. Overall, the emotional components of the SF-36 correlated better with Skindex-Emotion than the HAQ-DI. The SF subscore of the SF-36 correlated significantly more to the Skindex-Emotion than the HAQ-DI correlated to the Skindex-Emotion. There was no significant difference between the correlations of the physical components of the SF-36 to the PtGA compared and the correlation between the HAQ-DI and PtGA (See Table 6). The HAQ-DI and all SF-36 subscores, except for RE and MH, were found to have a significant correlation to the overall PGA (Table 6).
The above results indicate that DM has a significant impact on QoL even when compared to various other dermatologic and non-dermatologic diseases. Using the Skindex-29, DM was found have a significantly worse impact on the emotional realm of QoL compared to several other diseases. Based on the results of a global health QoL instrument, the SF-36, DM patients were found to have a significantly worse mental health, representing overall mood, than patients representing all of the compared diseases except CLE, SLE, and clinical depression, which all had significantly worse mental health scores than DM. This is an important conclusion for multiple reasons. Firstly, although it well-established that psychiatric co-morbidities are often present in dermatology, it has also been shown that dermatologists frequently do not identify self-reported psychiatric disease patients10–14,16, 17,44,45. Furthermore, a study of 1580 psoriasis patients in 39 Italian dermatology centers showed that dermatologists do not tend to modify their clinical approach to include psychosocial interventions for patients when psychological distress is present46,47. This is especially alarming as patients who have suicidal ideations have significantly higher Skindex-29 subscores (subscore means ranging from 44.3 to 49.5) than those who do not have suicidal ideations (subscore means ranging from 18.6 to 32.1) 48. Consequently, it is important to realize that DM patients may be an under-served population in terms of being evaluated by clinicians for psychological well-being. Secondly, there is increasing evidence in the field of psychoneuroimmunology supporting the role of psychological and social factors influencing the state of disease, particularly in psoriasis, through production of pro-inflammatory cytokines46, 49, 50. Further investigations are needed to assess how psychological and social factors may influence the disease state in the DM population.
Our results also show that there is a significant correlation between cutaneous disease severity and QoL. This is in accordance to a previous study using a 5-point Likert PGA scale9. This has also been shown in a variety of other disease states, including acne, pemphigus, psoriasis, cutaneous lupus, and vitiligo10, 40–42, 51,5.
It has been suggested that pruritus may be useful in distinguishing between DM and lupus patients9, 19, 21. We have shown that prevalence of pruritus is significantly higher in DM than in the CLE population and that it correlates significantly with QoL (the latter finding being consistent with a previous study) 9. Though we have shown that the DM population experiences a significantly higher level of pruritus than the CLE population, further investigation is needed to determine its usefulness in distinguishing between the two diseases.
Though we were not able to achieve statistical significance, which likely was related to our small sample size, the data suggest that classic DM is associated with a worse QoL with respect to physical functioning. Investigations that assess QoL among the DM subtypes could shed light on this result.
By comparing the two skin-specific QoL instruments, we were able to show that the DLQI significantly correlates with each of the Skindex-29 subscores as well as pruritus. Given that the DLQI is a simpler, shorter skin-specific QoL instrument, this finding suggests that the DLQI may be more feasible for clinical use in DM patients where a more comprehensive outcome instrument such as the Skindex-29 is not needed (i.e. where QoL is not a primary outcome variable). It is important to note, however, that the DLQI contains only one question examining purely the emotional impact of skin disease. Given the result that the DLQI correlates with the Skindex-29 Function significantly better than to the Skindex-29 Emotion, and since we have shown that DM creates a significant emotional impact on patients, study instruments examining emotion more thoroughly may be more informative.
In a paper evaluating QoL instruments in psoriasis, the DLQI was noted to focus mainly on limitation, supporting our conclusion that the DLQI is an inadequate tool in the DM population since we have shown there is a significant emotional impact as well52. Comparing the two global health instruments, the SF-36 emotional subscores correlated better to the Skindex-Emotion than the HAQ-DI, suggesting that the SF-36 is a more useful instrument to assess the emotional components of QoL than the HAQ-DI. Since statistical significance was only achieved comparing the SF-36 Social Functioning score and the HAQ-DI, further research with a larger study population is needed to better demonstrate that the SF-36 is a better global medical QoL outcome instrument than the HAQ-DI to compare QoL in DM and other non-dermatologic diseases. Furthermore, in our study population, 38% scored the minimal score on the HAQ-DI, compared to 0% on the SF-36. This may suggest that the HAQ-DI may not be sensitive enough to detect minor disease in the DM population. Interestingly, in another study, 25.3% of the study population in rheumatoid arthritis had the HAQ-DI minimum score which may suggest that the HAQ-DI may create a positively-skewed distribution in multiple diseases 53. This conclusion, however, needs to be further assessed as the HAQ-DI has been used extensively, especially in arthritis populations.
Although we were able to make several conclusions from this study, a few limitations should be addressed. The study was cross-sectional and did not discriminate between those who had initiated treatment and those who had not. To fully explore the relationship between disease activity and QoL, future studies on the changes in QoL as disease activity changes are warranted. Secondly, the study is limited by the small study population. A larger patient population needs to be studied to further assess QoL in DM patients, specifically to better compare DM subtypes and to better compare DM to the other diseases. Thirdly, two study populations were used, namely one population at the University of Pennsylvania and the other at Stanford University. Thirdly, as both study centers are in referral centers, it is possible that our study population may not represent the DM population as a whole.
This material is based upon work supported by the National Institutes of Health, including NIH K24-AR 02207 (Werth), NIH K24 AR052667 (Chren), and training grant NIH 5-R25-HL084665-04 (Goreshi). This work was also partially supported by a Merit Review Grant from the Department of Veterans Affairs Veterans Health Administration, Office of Research and Development, Biomedical Laboratory Research and Development.
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Conflicts of Interest: Honoraria from Amgen, Centocor, Chemocentryx, and MedImmune (Fiorentino), grants from Centocor, Abbott labs, Amgen (Fiorentino), and a filed patent (U.S. Patent Application Serial Number 12/694,980 for:“Profiling for Determination of Response to Treatment for Inflammatory Disease”, filed on 1/27/2010)(Fiorentino) is also being disclosed.
Prior Presentation: An poster and abstract of this study, with a smaller number of study subjects, was accepted to the Society of Investigative Dermatology Annual Meeting in May 2010 and published in the Journal of Investigative Dermatology Volume 130 Supplement 1 April 2010 pg S54, respectively.