The Dermatology Life Quality Index (DLQI) is an easy and practical way of quantifying the impact of skin disease. The role of DLQI in treatment guidelines and its emergence as an eligibility and response criterion in health technology appraisal are discussed. This review analyzes the current available literature on the clinical use of the DLQI, with particular reference to its relationship with disease severity and as a criterion in the assessment of health technology. The need for future studies of chronic hand eczema to incorporate DLQI to document quality-of-life outcomes with new treatments is also discussed.
Skin diseases are very common in the community and although most are not life threatening, many are chronic and incurable. Skin diseases significantly affect patients’ quality of life (QOL), due to several issues including chronic, disabling, and disfiguring nature, with symptoms such as discomfort and additional associated stigma. These effects on patients may not be captured using traditional biomedical outcome measures, and hence QOL assessment has become an important end point in clinical trials in addition to traditional clinical outcomes. Moreover, QOL is increasingly being incorporated into routine clinical practice, patient service evaluation, and policy making and for health resource allocation. The use of QOL and other patient-reported outcomes have become a regulatory requirement for the pharmaceutical industry in supporting labeling claims.
The Dermatology Life Quality Index (DLQI) was developed in 1994, and today is the most commonly used dermatology-specific QOL measure in clinical trials of skin diseases. The DLQI has been used in more than 36 skin diseases (inflammatory, noninflammatory, and skin cancers) in more than 32 countries and is available in more than 55 international language versions. The DLQI has been shown to be easy to use in clinical practice because of its simplicity and brevity, with an average completion time of approximately 2 minutes. It consists of 10 questions concerning dermatologic patients’ perception of the impact of skin diseases on different aspects of their QOL over the last week. The items of the DLQI encompass aspects such as symptoms and feelings, daily activities, leisure, work or school, personal relationships, and the side effects of treatment. Each item is scored on a 4-point scale: not at all/not relevant, a little, a lot, and very much. Scores of individual items (0–3) are added to yield a total score (0–30); higher scores mean greater impairment of a patient’s QOL. In 2005, Hongbo and colleagues introduced the much needed banding of the DLQI scores to facilitate the clinical interpretation of scores. According to this banding system, a DLQI score of 0 and 1 means no impact on a patient’s QOL whereas a score of 2 to 5, 6 to 10, 11 to 20, and 21 to 30 indicates a small, moderate, large, and an extremely large effect on patient’s QOL, respectively. Psychometrically, the DLQI has been shown to be a strong instrument regarding its internal consistency, reproducibility, validity, and sensitivity to change. The DLQI has been used in descriptive and evaluative studies in various countries, and has also been incorporated into various treatment guidelines as well as cost-of-illness and cost-effectiveness analysis studies.
This nonsystematic review gives an overview of the use of the DLQI as an outcome in clinical research and Health Technology Assessment in psoriasis and chronic hand eczema (CHE) with particular emphasis on determining the severity of these 2 conditions based on DLQI scores.
Literature search strategy
The review involved a comprehensive search of literature in electronic databases, including Ovid, MEDLINE, EMBASE, PubMed, Google Scholar, and the Cochrane Library, from 1994 to the present using search terms such as quality of life, DLQI, psoriasis, hand dermatitis, and CHE. The references of articles were also hand-searched.
Clinical use of the DLQI in psoriasis
Psoriasis is a chronic immune-mediated inflammatory skin disease characterized by scaly red plaques. The incidence of psoriasis in European countries has been estimated to be 1.5% to 2%. This disfiguring skin condition not only significantly affects sufferers’ QOL but also is associated with loss in productivity and substantial economic burden on society. The impact of psoriasis on patients’ lives has been found to be comparable to the impact of many chronic systemic illnesses, such as heart diseases, diabetes, cancer, depression, and chronic respiratory conditions. The latest evidence suggests that psoriasis should be considered a systemic illness because of its frequent association with comorbidities, such as metabolic syndrome, cardiovascular diseases, arthritis, and psychiatric diseases.
Conventionally, severity of psoriasis has been based on the magnitude and extent of physical signs and/or total body surface area (BSA) affected, as is reflected by the commonly used objective disease severity tool, Psoriasis Area and Severity Index (PASI). However, PASI and other similar objective tools do not capture the actual severity of the disease from the patients’ perspective and the impact on their lives that may be much greater than the visible severity measured by these tools. Nevertheless, because of the unavailability of a universal tool that could assess the impact on patients based on both physical severity and QOL impairment, the PASI has become the most widely used disease severity outcome measure in clinical trials.
Introduction of the “rule of tens” was an effort to define the concept of psoriasis severity in relationship to QOL in simple terms. According to this rule, psoriasis should be considered severe if a patient’s DLQI score or BSA or PASI is more than 10. These 3 parameters have also been used to define the treatment goals for psoriasis therapy in clinical trials. A DLQI score of 0 or 1 has been suggested as a treatment goal after 10 to 16 weeks of antipsoriasis therapy, whereas a DLQI score reduction of at least 5 points (the minimal clinically important difference of the DLQI) is required to demonstrate the minimum efficacy achieved by the therapy. Similarly, the British Association of Dermatologists (BAD) has defined the treatment response as a minimum of a 5-point reduction in the DLQI scores along with 50% PASI reduction. Although in a review of randomized controlled trials of biologics the improvement in the DLQI scores was shown to be paralleled by a similar PASI improvement, the DLQI may be better than PASI at capturing information regarding treatment benefit from patients’ perspective and should therefore be given more weight.
Based on the rule of tens definition of severe psoriasis, a DLQI score of more than 10 has been adopted as an essential eligibility criterion in both the BAD ( Table 1 ) and National Institute for Health and Clinical Excellence (NICE, Table 2 ) guidelines for biological intervention of psoriasis. Although the BAD guidelines require a minimum DLQI score of more than 10 consistently for all licensed biologics, the NICE guidelines for infliximab require a DLQI score of more than 18 (and PASI of 20 or more) and more than 10 for the rest of licensed biologics. The guidelines for biological intervention in some other countries such as Italy have similar criteria to those in the BAD guidelines. According to the European Dermatology Expert Group, which has given recommendations for the use of etanercept for psoriasis, moderate to severe psoriasis has been defined by a PASI of 10 or a BSA of 10, or a DLQI score of 10.
| Criteria | Other | Assessment of Response (wk) | Criteria for Adequate Response | |
|---|---|---|---|---|
| Infliximab | Severe plaque psoriasis PASI ≥10 and DLQI >10 |
| 14 (license) | PASI 75 from baseline or PASI 50 and 5-point reduction in DLQI |
| Etanercept | Severe plaque psoriasis PASI ≥10 and DLQI >10 | 12 | PASI 75 from baseline or PASI 50 and 5-point reduction in DLQI | |
| Adalimumab | Severe plaque psoriasis PASI ≥10 and DLQI >10 | 16 | PASI 75 from baseline or PASI 50 and 5-point reduction in DLQI | |
| Ustekinumab | Severe plaque psoriasis PASI ≥10 and DLQI >10 | 28 (license) | PASI 75 from baseline or PASI 50 and 5-point reduction in DLQI |
a Cyclosporine (2.5 mg/kg once daily; up to 5 mg/kg once daily); and in men, and women not at risk of pregnancy, methotrexate (single dose [oral, subcutaneous intramuscular] of 15 mg weekly; maximum 25 mg weekly) and acitretin (25–50 mg daily).
| Criteria | Other | Assessment of Response (wk) | Criteria for Adequate Response | |
|---|---|---|---|---|
| Infliximab | Very severe plaque psoriasis PASI ≥20 and DLQI >18 | Failure to respond/intolerant of/contraindication to standard systemic therapies a | 10 | PASI 75 from baseline or PASI 50 and 5-point reduction in DLQI |
| Etanercept | Severe plaque psoriasis PASI ≥10 and DLQI >10 | 12 | PASI 75 from baseline or PASI 50 and 5-point reduction in DLQI | |
| Adalimumab | Severe plaque psoriasis PASI ≥10 and DLQI >10 | 16 | PASI 75 from baseline or PASI 50 and 5-point reduction in DLQI | |
| Ustekinumab | Severe plaque psoriasis PASI ≥10 and DLQI >10 | 16 | PASI 75 from baseline or PASI 50 and 5-point reduction in DLQI |
Clinical use of the DLQI in psoriasis
Psoriasis is a chronic immune-mediated inflammatory skin disease characterized by scaly red plaques. The incidence of psoriasis in European countries has been estimated to be 1.5% to 2%. This disfiguring skin condition not only significantly affects sufferers’ QOL but also is associated with loss in productivity and substantial economic burden on society. The impact of psoriasis on patients’ lives has been found to be comparable to the impact of many chronic systemic illnesses, such as heart diseases, diabetes, cancer, depression, and chronic respiratory conditions. The latest evidence suggests that psoriasis should be considered a systemic illness because of its frequent association with comorbidities, such as metabolic syndrome, cardiovascular diseases, arthritis, and psychiatric diseases.
Conventionally, severity of psoriasis has been based on the magnitude and extent of physical signs and/or total body surface area (BSA) affected, as is reflected by the commonly used objective disease severity tool, Psoriasis Area and Severity Index (PASI). However, PASI and other similar objective tools do not capture the actual severity of the disease from the patients’ perspective and the impact on their lives that may be much greater than the visible severity measured by these tools. Nevertheless, because of the unavailability of a universal tool that could assess the impact on patients based on both physical severity and QOL impairment, the PASI has become the most widely used disease severity outcome measure in clinical trials.
Introduction of the “rule of tens” was an effort to define the concept of psoriasis severity in relationship to QOL in simple terms. According to this rule, psoriasis should be considered severe if a patient’s DLQI score or BSA or PASI is more than 10. These 3 parameters have also been used to define the treatment goals for psoriasis therapy in clinical trials. A DLQI score of 0 or 1 has been suggested as a treatment goal after 10 to 16 weeks of antipsoriasis therapy, whereas a DLQI score reduction of at least 5 points (the minimal clinically important difference of the DLQI) is required to demonstrate the minimum efficacy achieved by the therapy. Similarly, the British Association of Dermatologists (BAD) has defined the treatment response as a minimum of a 5-point reduction in the DLQI scores along with 50% PASI reduction. Although in a review of randomized controlled trials of biologics the improvement in the DLQI scores was shown to be paralleled by a similar PASI improvement, the DLQI may be better than PASI at capturing information regarding treatment benefit from patients’ perspective and should therefore be given more weight.
Based on the rule of tens definition of severe psoriasis, a DLQI score of more than 10 has been adopted as an essential eligibility criterion in both the BAD ( Table 1 ) and National Institute for Health and Clinical Excellence (NICE, Table 2 ) guidelines for biological intervention of psoriasis. Although the BAD guidelines require a minimum DLQI score of more than 10 consistently for all licensed biologics, the NICE guidelines for infliximab require a DLQI score of more than 18 (and PASI of 20 or more) and more than 10 for the rest of licensed biologics. The guidelines for biological intervention in some other countries such as Italy have similar criteria to those in the BAD guidelines. According to the European Dermatology Expert Group, which has given recommendations for the use of etanercept for psoriasis, moderate to severe psoriasis has been defined by a PASI of 10 or a BSA of 10, or a DLQI score of 10.
| Criteria | Other | Assessment of Response (wk) | Criteria for Adequate Response | |
|---|---|---|---|---|
| Infliximab | Severe plaque psoriasis PASI ≥10 and DLQI >10 |
| 14 (license) | PASI 75 from baseline or PASI 50 and 5-point reduction in DLQI |
| Etanercept | Severe plaque psoriasis PASI ≥10 and DLQI >10 | 12 | PASI 75 from baseline or PASI 50 and 5-point reduction in DLQI | |
| Adalimumab | Severe plaque psoriasis PASI ≥10 and DLQI >10 | 16 | PASI 75 from baseline or PASI 50 and 5-point reduction in DLQI | |
| Ustekinumab | Severe plaque psoriasis PASI ≥10 and DLQI >10 | 28 (license) | PASI 75 from baseline or PASI 50 and 5-point reduction in DLQI |
a Cyclosporine (2.5 mg/kg once daily; up to 5 mg/kg once daily); and in men, and women not at risk of pregnancy, methotrexate (single dose [oral, subcutaneous intramuscular] of 15 mg weekly; maximum 25 mg weekly) and acitretin (25–50 mg daily).
Related posts:
Health-Related Quality of Life in Dermatology: Introduction and Overview
Overview of Health Status Quality-of-Life Measures
Melasma Quality of Life Measures
Quality-of-Life Instruments: Evaluation of the Impact of Psoriasis on Patients
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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