Health-related quality of life (QoL) is a patient-reported outcome that describes the impact of the disease in question to all aspects of persons’ life, including psychosocial, emotional, physical, and functional impact. As such, health-related QoL is particularly relevant in conditions that have no physical signs and need to rely on patient reports to know whether they are improving or not. Work is beginning in pruritus to develop instruments that can measure pruritus-related QoL. This article reviews the instruments that have been developed and used in pruritus and also reviews the literature regarding the impact of pruritus on QoL.
Pruritus is the Rodney Dangerfield of medicine, and perhaps even dermatology, because it commands very little respect relative to other symptoms. Why would this be the case? The definition of itch originated more than 340 years ago when Hafenreffer, a German physician, characterized itch as an unpleasant sensation, provoking the desire to scratch. Since then, pruritus has been increasingly recognized as a common symptom. Population-based epidemiologic data are sparse; however, several recent studies have yielded data supporting this claim. Wolkenstein and colleagues attempted to evaluate the prevalence and impact of main dermatologic disorders in France. From their data for skin conditions in which pruritus is commonly associated, the prevalence of pruritus can be extrapolated to be between 20% and 35%. Matterne and colleagues performed a population-based cross-sectional study in the general German population with the specific aim of determining the prevalence of chronic pruritus. The investigators found a point prevalence of 13.5% (95% confidence interval [CI], 12.2%–14.9%), 12-month prevalence of 16.4% (95% CI, 15.0%–17.9%), and lifetime prevalence of 22.0% (95% CI, 20.4%–23.7%). Our preliminary data from nationally sampled US veterans suggest that 30% of veterans have suffered from chronic pruritus.
Data also suggest that diagnoses in which itch is often a primary symptom rank as the most common cutaneous diagnoses treated. An example of a skin condition in which pruritus is common is psoriasis. Globe and colleagues used physician interviews and patient focus groups to characterize the impact of itch symptoms when developing a disease model for psoriasis. Dermatologists most frequently mentioned pruritus as a major psoriasis symptom followed by arthralgia/arthritis, flaking, and pain. They also rated the importance of itch to patients highly (8–10 out of 10). In focus groups of patients with both severe and mild psoriasis, the overwhelming majority of the patients rated itch as the most important (31/39), most severe (31/39), and most troublesome (24/39) symptom and noted that itch negatively affected daily activities (eg, concentration, sleep, ability to attend work or school) as well as emotions (eg, anxiety and embarrassment).
However, the cause of chronic pruritus is not only from cutaneous disorders but also from systemic diseases such as uremia and liver failure or because of unknown origin. Weisshaar and colleagues compared 2 populations with pruritus, one in Germany (132 patients) and one in Uganda (84 patients). Although 57% of the German patients had pruritus due to dermatoses, 36% had pruritus due to a systemic disease and 8% had pruritus of unknown origin. Affective reactions such as aggression and depression occurred more frequently in patients with dermatologic problems than those with systemic pruritus. The former group felt that pruritus had a greater impact on their lives. Almost all Ugandan patients had pruritus due to dermatoses, except for 3 with pruritus of unknown origin. Patients with pruritus in both populations showed an impaired quality of life (QoL).
Although pruritus has being recognized as a common symptom and although a core group of investigators have made progress in unraveling the pathophysiologic pathways of pruritus, very few treatment options exist and exceedingly little research is being conducted to fill this void. One could argue that the study of pruritus is stunted and frustrating because it is not visible and is difficult to measure. However, other nonvisible symptoms such as pain and nausea are well studied and, as a result, have many treatment options. Historically, investigators used instruments that measured the physical sequela of itch, such as scratching or rubbing. However, not everybody who itches manifests scratching.
There is an increasing recognition in health care research of the value of patient-reported outcomes. The simplest patient-reported outcome is the visual analog scale, asking patients to rank their itch on a scale that ranges from “No Itch” to “Most Severe Itch Imaginable or Experienced.” However, these scales are very limited in that they only address intensity and do not address health-related QoL issues.
Health-related QoL is a patient-reported outcome that describes the impact of the disease in question to all aspects of persons’ life, including psychosocial, emotional, physical, and functional impact. As such, health-related QoL is particularly relevant in conditions that have no physical signs and need to rely on patient reports to know whether they are improving or not. Work is beginning in pruritus to develop instruments that can measure pruritus-related QoL. This article reviews the instruments that have been developed and used in pruritus and also reviews the literature regarding the impact of pruritus on QoL.
Health-related QoL instruments that detail the specifics of how a disease or condition affects QoL come in 3 main flavors: generic health, organ specific, and disease condition specific. Generic health QoL questionnaires contain items that are common to all health conditions. As such, they can be applied across diseases and populations. However, general health QoL measures may not be sensitive enough to detect issues specific to a particular disease/condition and thus may not be responsive to changes. Organ-specific, in our case skin-specific, QoL instruments can be applied to all diseases/conditions within the skin, and thus the impact on QoL can be compared across skin disorders. More specific than general health QoL measures, these measures may still not be sensitive enough to detect issues specific to a particular disease/condition. Disease/condition-specific QoL instruments are the most sensitive to issues at hand with the disease/condition in question but may not be compared with other populations. As discussed in detail elsewhere in this issue, one can distinguish health status instruments, which define the state of itching for the patient, from QoL instruments that address the impact of itch on the psychosocial as well as the physical aspects of the patients’ lives. In this article, we attempt to identify health status instruments as such, recognizing that the labels of health status versus health-related QoL instruments are often blurred in the literature. There are preference-based health-related QoL measures that ask patients to quantify the amount of QoL impact in terms of a metric that they are willing to trade, such as risk, time, or money.
Methods
To determine the published literature establishing the QoL impact of pruritus, we conducted a limited systematic review. We queried PubMed with the key words of “pruritus” and “quality of life” and obtained 528 articles. We eliminated those articles without at least an English abstract and those articles that did not have “pruritus” and a construct related to QoL in the title. This filtering left 25 articles, of which 8 related to instrument development or translation and 2 related to epidemiology, which are discussed previously.
Results
Generic Health Instruments in Pruritus
One of the most commonly used generic health instruments was developed from the Medical Outcomes Study, called the Short Form 36 (SF-36). SF-36 is a measure of health status and consists of 8 scaled scores that are the weighted sums of the questions in each section. The 8 sections are vitality, physical functioning, body pain, general health perceptions, physical role functioning, emotional role functioning, social role functioning, and mental health. The SF-36 has been subsequently pared to a 12-item version, the SF-12, which consists of a physical health component and a mental health component. Specifically, the SF-12 addresses general health, daily and social activity limitations as a result of physical and/or mental health, impact of pain on normal work, as well as feelings of calm and peace, energy, and downheartedness/blue. Scores from both versions are compared with norms developed from a US general population.
Our search revealed 3 studies that used the Short Form instruments to investigate the impact of pruritus, one of which is discussed in this review because they also used a skin-specific QoL instrument. Paul and colleagues examined itch in chronic venous disease. Their study was part of a larger investigation into the impact of intravenous drug use on the distribution and severity of chronic venous disorders. The 161-subgroup cohort evaluated for pruritus completed the SF-12 as well a visual analog scale for itch intensity. Using the clinical score of the Clinical-Etiology-Anatomy-Pathophysiology classification of the worst leg, the most common classification was Class 3, edema without skin changes (45.9%); 18.6% had severe venous disease (Classes 5 and 6). Eighty-eight participants (54.7%) reported itch somewhere on their body, with 74 of them (45.9%) reporting itch on the legs or feet. Persons with leg or feet itch had poorer scores on the physical component of the SF-12 than those without itch. The 2 groups did not differ significantly on the mental health component. One possible reason that there was no significant difference in the mental health scores is that the items in SF-12 are not sensitive enough to the emotional impact of pruritus. However, compared with the US norms, persons with itch were more than 1 SD below the mean for both their mental (57.45) and physical health (34.79) scores. The investigators concluded that legs or feet itch has lower QoL and is a clinically relevant problem that is related to the level of venous disease.
El-Baalbaki and colleagues explored the association of pruritus with QoL and disability in 578 patients with systemic sclerosis after 1 or more years postenrollment in the Canadian Scleroderma Research Group Registry. Patients reported whether they experienced pruritus during the past month on most days and completed the SF-36. Disability was measured with the Health Assessment Questionnaire disability index. However, only the abstract was available, so scores for the assessments were not attainable. The investigators described that a total of 248 patients (43%) reported pruritus on most days. Patients with pruritus had significantly worse mental (Hedges g = −0.43; 95% CI, −0.59 to −0.26) and physical function (Hedges g = −0.51; 95% CI, −0.68 to −0.34) and greater disability (Hedges g = 0.46; 95% CI, 0.29 to 0.63) than those without pruritus. In multivariate analyses, controlling for age, sex, marital status, education, disease duration, skin score, number of tender joints, gastrointestinal symptoms, breathing problems, Raynaud phenomenon, and finger ulcers, pruritus was independently associated with mental ( P = .017) and physical function ( P = .003) but not disability ( P = .112). The investigators concluded that pruritus is common and associated with QoL in systemic sclerosis.
Another general health instrument is the Symptom Checklist-90-R (SCL-90-R), which is designed to evaluate a broad range of psychological problems and symptoms of psychopathology. The 90 items yield 9 scores along primary symptom dimensions, including somatization, obsessive-compulsive disorder, interpersonal sensitivity, depression, anxiety, hostility, phobic anxiety, paranoid ideation, and psychoticism. van Os-Medendorp and colleagues used the SCL-90-R to determine the predictors of psychosocial morbidity in patients with chronic pruritic skin diseases. They hypothesized that feelings of helplessness and lack of control can influence the perceived itch and psychosocial complaints. The investigators recruited 168 patients with pruritic skin diseases from 5 hospitals in the Netherlands. Skin-related psychosocial morbidity was measured with the Adjustment to Chronic Skin Diseases questionnaire (ACS); general psychosocial morbidity was measured with the Symptom Checklist-90 (SCL-90). The frequency and intensity of itching and scratching was recorded in diaries. Itch-related coping was measured with the Itching Cognitions Questionnaire. The investigators found that patients with pruritic skin diseases had higher SCL-90 scores than a healthy Dutch population. All patients had psychosocial complaints as measured with the ACS. About 39% of the variance in skin-related psychosocial morbidity was explained by catastrophizing and helpless coping; another 11% was explained by itching and scratching. Age and sex together explained another 10%. The frequency of itching and scratching (11%), catastrophizing and helpless coping (19%), and skin-related psychosocial morbidity (10%) explained the variance in general psychosocial morbidity. The investigators concluded that patients with a pruritic skin disease have a high level of psychosocial morbidity. Catastrophizing and helpless coping are the most important predictors of psychosocial morbidity, with itching, scratching, and demographic variables having a limited influence.
Skin-Specific QoL Instruments
Skin-specific QoL instruments have been developed and validated to measure the QoL impact for all skin disorders. The 2 most commonly used instruments, the Skindex and the Dermatology Life Quality Index (DLQI), have items that relate to pruritus. The DLQI, a frequency-based measure, has an item that asks, “Over the last week, how itchy, sore, painful or stinging has your skin been?” which should be noted to combine pruritus with 3 other symptoms. The Skindex-29, which describes the frequency of impairment to QoL, has 1 item that asks the frequency of “My Skin Itches,” whereas the Skindex-16, which describes the level of bother for a QoL impairment, has an item that asks, “During the past week, how often have you been bothered by your skin condition itching?” Because both instruments ask items that relate to QoL impairment, one can ascertain the difference in QoL impairment when comparing those that itch more with those that do not. However, the way that the items are referred to “Your Skin Condition” can be problematic when trying to distinguish whether the QoL impact is purely because of the symptom of pruritus or some other aspect of the skin condition, such as appearance.
DLQI application in pruritus
The DLQI is the most commonly used skin-specific health status measure. It consists of 10 questions querying how symptoms and feelings, daily activities, leisure, work, school, personal relationships, and treatment were affected by skin disease over the previous week. It has been reviewed in detail elsewhere in this issue but should be noted to primarily address disability rather than emotional impact of skin conditions. In addition, clinical meaning has been assigned to bands of DLQI scores: 0 to 1, no effect; 2 to 5, small effect; 6 to 10, moderate effect; 11 to 20, very large effect; and 21 to 30, extremely large effect on patient’s QoL. The DLQI was the instrument of choice in evaluating pruritus or skin diseases in which pruritus is a major symptom in 6 articles in our systematic review.
Chularojanamontri and colleagues performed a cross-sectional study, administering a Thai version of the DLQI in patients with systemic sclerosis who attended the Department of Dermatology, Siriraj Hospital in Bangkok, Thailand, between August 2009 and April 2010. A total of 80 patients with systemic sclerosis were enrolled in this study. Twelve patients had limited disease, whereas 68 patients had diffuse sclerosis. DLQI scores were not reported or correlated to pruritus. However, the investigators note that pain/pruritus was the most significant problem in patients, whereas the salt-and-pepper appearance was the cutaneous finding that had association with high DLQI scores. The investigators concluded that the treatment of pain and pruritus and prominent cutaneous findings should be taken into account to improve the QoL of patients with systemic sclerosis.
Szepietowski and colleagues surveyed 334 patients with end-stage renal disease with moderate to severe uremic xerosis for QoL assessment using the DLQI. Pruritus was self-assessed by patients, using a visual analog scale. Those subjects who reported pruritus had greater QoL impact than those who did not (5.99 ± 4.82 [moderate effect] vs 3.24 ± 3.99 [small effect], P <.001). Using a multiple linear regression model, the investigators found that age and pruritus intensity, but not xerosis intensity, were found to be independent contributors to DLQI deterioration ( P <.0005). On the other hand, uremic xerosis without associated pruritus still resulted in DLQI alteration (3.24 ± 3.99). It was concluded that young age and intensity of uremic pruritus compromise QoL in patients with uremic xerosis. Some characteristics of uremic xerosis other than xerosis intensity may also be involved in QoL alteration.
The DLQI was also used to determine the impact of pruritus on QoL in sulfur mustard–exposed Iranian veterans. The rationale for this study is that one of the foremost negative effects of sulfur mustard, a chemical warfare agent, is chronic pruritus. The DLQI and a pruritus visual analog scale were administered to 125 consecutive chemically injured veterans suffering from pruritus. The distribution of subjects according to pruritus severity were as follows: 11%, mild; 35%, moderate; and 54%, severe itching with corresponding median DLQI scores of 16, 20, and 21, respectively ( P = .014). Of note, the scores of 16 and 20 fall within the clinical band of “Very Large Effect on QoL,” whereas 21 is the lower bound of “Extremely Large Effect on QoL.” The DLQI subscores of symptoms and feelings ( P = .015), personal relationships ( P = .002), and daily activities ( P = .036) were worst in patients with severe itching. The investigators concluded that chemically injured veterans suffering from severe itching have a significantly poorer QoL than patients with milder symptoms.
The DLQI was used in 2 studies for evaluation of pruritus in psoriasis. Zachariae and colleagues explored the possible association between different dimensions of pruritus to psychological symptoms and QoL impact. The investigators also explored the role of sleep impairment as a possible mediator of the association between pruritus and psychological symptoms and QoL. A sample of 40 patients with psoriasis completed a scale with descriptors from the Structured Itch Questionnaire together with measures of depression, distress, sleep quality, and the DLQI. Of note, the investigators modified the DLQI by omitting irrelevant items and items relating directly to perceived itch, thus preventing the calculation of an overall DLQI score. The investigators also rephrased items to refer directly to difficulties due to itch. Psoriasis severity was assessed with the Psoriasis Area and Severity Index. Factor analysis of descriptors confirmed both an affective (eg, unbearable, bothersome) and a sensory (eg, pinching, tickling) pruritus severity dimension. Multivariate statistics, controlling for age, gender, disease duration, and severity, showed affective, but not sensory, pruritus severity to be a significant predictor of depressive symptoms, global distress, impairment of sleep, and QoL. Mediation analyses indicated that impaired sleep quality partly mediated the association between pruritus severity and psychological symptoms. The investigators concluded that pruritus is multidimensional and that the affective dimension may be the most important predictor of pruritus-related psychological morbidity and that the association may be mediated by its negative impact on sleep quality.
Reich and colleagues used the DLQI to evaluate the relationship between pruritus and the well-being of patients with psoriasis. The mean DLQI score of the 91 patients who reported pruritus (of total 102 patients with psoriasis) was 12.2 ± 7.0. Patients with pruritus had significantly decreased QoL compared with those without report of pruritus (12.2 ± 7.0 vs 6.8 ± 7.1, P = .02 or very large vs moderate impact). The investigators also found that pruritus intensity correlated with feelings of stigmatization, stress, and depressive symptoms. They concluded that pruritus may have a significant negative influence of the psychosocial status of patients with psoriasis.
A pediatric version of the DLQI, the Children’s Dermatology Life Quality Index (CDLQI), was administered to children with atopic dermatitis to evaluate improvement with pruritus after they and their families joined support groups. The investigators based their study on preliminary evidence suggesting that support groups and educational programs are helpful in reducing stress, disease, and pruritus severity and improving QoL. Thirty-two patients and their relatives completed the questionnaires satisfactorily. The baseline overall QoL as measured by the CDLQI was 11.37 ± 7.26, which corresponds to “Very Large Effect” on the clinical interpretation of DLQI scores. The investigators noted significant change in CDLQI scores ( P <.01) as well as specific domains, such as personal relationships ( P = .02) and leisure ( P = .04) with their intervention but did not report correlations with pruritus improvement. Thus, although the investigators concluded that support groups may be very effective accessory tools in the management of recalcitrant forms of atopic dermatitis, it is unclear regarding the relative impact of pruritus versus other aspects of atopic dermatitis improvement on the QoL benefits.
Skindex application
The Skindex instruments were designed to measure the effects of skin disease on health-related QoL across different populations and to aid in assessing change in this parameter in individual patients. The Skindex-29 addresses frequency of items, whereas the Skindex-16 addresses level of bother. Similar to the DLQI, the Skindex has been extensively psychometrically tested. In addition, the Skindex has a broad emotional component that the DLQI lacks and can be reported as subscales of emotion, symptoms, and functional impact. The Skindex was used in 3 articles to measure QoL impact of itch.
Murota and colleagues used the Skindex-16 to measure the impact of sedative and nonsedative antihistamines in patients with pruritic skin diseases in Japan. The investigators also examined work productivity and used a visual analog scale to measure itch intensity. They found that in 216 patients with pruritic skin diseases, there was a significant impairment of work, classroom, and daily productivity. All pruritic diseases in this study negatively affected daily activity to a similar degree. No scores and only correlations were reported for the Skindex results. The Skindex-16 change scores correlated well with changes in pruritus visual analog scale score (r = 0.58, P <.001) for the group that took the nonsedative antihistamines, whereas there was no significant correlation in the sedative antihistamine group. This may be explained by their finding that nonsedative antihistamines produced greater overall improvements in productivity than sedative antihistamines. However, this explanation also suggests that the Skindex might be measuring more than just pruritus-specific QoL impact.
Tessari and colleagues examined the impact of pruritus on the QoL of 169 patients undergoing both hemodialysis (HD) and peritoneal dialysis (PD) using the Skindex-29. The investigators measured pruritus intensity on a visual analog scale and health status using the SF-36 and the General Health Questionnaire. Only the abstract was available to us, so we could not ascertain if SF-36 and Skindex scores were published. Pruritus was found in 52% of patients, with no differences between patients undergoing HD and PD. Prevalence of poor sleep in patients with pruritus was higher than in those without pruritus (59% vs 11%; P <.001). Neither physical nor mental scores of SF-36 correlated with the presence and the intensity of pruritus. Pruritus intensity was significantly related to poor scores in all 3 subscales of Skindex-29. This finding confirms the higher sensitivity of the skin-specific instrument as compared with the generic health instrument in measuring pruritus-specific impact on QoL. In the subscales of social function and emotions, worse scores were observed in patients undergoing HD and with minor psychiatric disorders. The investigators concluded that pruritus had a high level of impact on all aspects of QoL and was a predictor of poor sleep.
Duque and colleagues explored the prevalence and QoL impact of itch, pain, and burning sensation in a convenience sample of 100 patients with mild to moderate chronic venous insufficiency. Patients who suffered from itch were assessed with a visual analog scale for itch intensity and a modified Skindex-16 questionnaire. The investigators did not explicitly detail how the Skindex was modified. The prevalence of itch was 66%. Concomitant itch and burning sensation as well as itch and pain were noted in 47% and 44% of the patients, respectively. However, Skindex item and scale scores were not reported; only correlations with itch intensity were reported. The investigators reported a statistically ( P <.05) significant negative relationship between itch intensity and bother by itch (r = 0.5), persistence (r = 0.2), being irritated (r = 0.2), feelings of frustration (r = 0.2), and depression (r = 0.4). Functionally, the itch intensity was correlated with the desire to be with other people (r = 0.3), with the desire to develop daily activities (r = 0.4), and with what they enjoy (r = 0.3). The investigators note that the intensity of itch was comparable to that of other populations that they have studied: uremic pruritus, urticaria, and psoriasis. In addition, despite the correlation analysis, the investigators conclude that patients did not attribute emotional distress to the sensation of itch, differing from their findings with patients with psoriasis and atopic dermatitis. Nevertheless, the investigators concluded that their study found that itch, pain, and burning sensation are common symptoms of mild to moderate chronic venous insufficiency with a significant impact on QoL.
Pruritus-specific instruments
Both pruritus health status instruments, which define the state of itching for the patient, and pruritus-specific QoL instruments, which address the impact of itch on the psychosocial as well as the physical aspects of the patients’ lives, have been developed. One of the first pruritus-specific instruments to be developed is the Eppendorf Itch Questionnaire (EIQ) that is based on the long form of the McGill Pain Questionnaire. The instrument consists of 40 descriptive adjectives describing the itch sensation and 40 more descriptors of emotional aspects of itch. Investigators have critiqued the EIQ for not measuring QoL ; however, the instrument does address some emotional aspects of QoL, especially with items such as “Annoying,” “Bothersome,” and “Torturing.”
Another pruritus-specific instrument is the Short-Form Itch Questionnaire by Yosipovitch and colleagues. This questionnaire was based on the short-form McGill Pain Questionnaire, which is a multidimensional instrument designed to measure the impact of chronic pain and has been translated into other languages such as Canadian French. In addition to pruritus history, severity, and characteristics, there are questions that relate to QoL. The investigators define QoL items as those that ask about mood change, eating habits, as well as sexual desire and function, but they also ask about the impact of sleep, which can be considered a functional impact of QoL. The investigators developed questions as to how daily activities affect pruritus but do not ask how pruritus affects daily activities. The questionnaire also contained several items that were termed affective dimensions and consisted of the itch being bothersome, annoying, unbearable, and worrisome. The questionnaire was tested in a cohort of patients with uremia and found to have reasonable test-retest reliability (r = 0.72, P <.01).
Our review of the literature revealed 5 articles that used the Yosipovitch Short Form Itch Questionnaire. Two involve the population with uremia on which the questionnaire was developed, and the others include patients with at least 30% body involvement of psoriasis, chronic idiopathic urticaria, and atopic dermatitis, all populations from Singapore. All these patients had significant QoL impact because of their symptom of pruritus ( Table 1 ).
Related posts:
Health-Related Quality of Life in Dermatology: Introduction and Overview
Overview of Health Status Quality-of-Life Measures
Quality-of-Life Issues in Vitiligo
Melasma Quality of Life Measures
Clinical Meaning in Skin-specific Quality of Life Instruments: A Comparison of the Dermatology Life Quality Index and Skindex Banding Systems
Future Directions in Dermatology Quality of Life Measures
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