Dermatology Life Quality Index

Each question is scored on a four-point Likert scale:

• Very much = 3
• A lot = 2
• A little = 1
• Not at all = 0
• Not relevant = 0
• Question unanswered = 0

The DLQI is calculated by adding the score of each question, resulting in a maximum of 30 and a minimum of 0. The higher the score, the more quality of life is impaired. A score higher than 10 indicates that the patient's life is being severely affected by their skin disease.

The score can be expressed as a percentage of the maximum possible score of 30, but we don't recommend this, because the original score is much easier to understand.

The scores associated with the different answers should not be printed on the DLQI itself, as this might cause bias.

Scoring question 7

The first part of question 7 asks: 'Over the last week, has your skin prevented you from working or studying?'

If working or studying are not relevant to the subject, the response is 'Not relevant' (scored 0).

If the skin disease has prevented the subject from working or studying, the answer is 'Yes'. As 'prevention' is the biggest possible impact it is scored the maximum, 3.

If the skin disease has not prevented the subject from working or studying, the answer is 'No'. It is therefore assumed that as the skin disease has not prevented the subject from working or studying, the subject is able to continue to work or study, but that the skin disease may be a problem while doing so.

The subject is therefore asked the following question about the magnitude of the impact thus: 'If "No" (in other words 'If the skin disease has not prevented you from working or studying”), over the last week how much has your skin been a problem at work or studying?'

There are three possible responses to the question 'How much has your skin been a problem at work or studying': 'A lot' (scored 2), 'A little' (scored 1) or 'Not at all' (scored 0).

Meaning of scores

• 0-1 = no effect at all on patient’s life
• 2-5 = small effect on patient’s life
• 6-10 = moderate effect on patient’s life
• 11-20 = very large effect on patient’s life
• 21-30 = extremely large effect on patient’s life

Minimal clinically important difference (MCID)

For general inflammatory skin conditions, a change in DLQI score of at least four points is considered clinically important.

Sub-scales

The Dermatology Life Quality Index can be analysed under six sub-scales:

The scores for each of these sections can also be expressed as a percentage of either 6 or 3.

Missing data

If one question is unanswered, this is allocated a score of 0 and the DLQI score summed in the usual way, out of 30. If two or more questions are unanswered, the questionnaire is not scored.

It has been suggested that if there are one or more questions unanswered, an adjusted score should be calculated based on the percentage of the maximum score possible. We don't recommend this, and our reasons are given in the publication:

Finlay AY, Sampogna F. What do scores mean? Informed interpretation and clinical judgement are needed .Br J Dermatol 2018; 179: 1021-1022.

Scoring of DLQI sub-scales: If one question is left unanswered, the corresponding sub-scale should not be scored.  It would not be appropriate to draw any conclusions from a subscale unless the subscale were fully answered.

The DLQI and the translations are extensively validated.

The original publication covers the initial validation process:
Finlay AY, Khan GK. Dermatology Life Quality Index (DLQI): A simple practical measure for routine clinical use. Clinical and Experimental Dermatology 1994; 19: 210-216.

This review article covers multiple aspects of validation data up to 2008:
Basra MKA, Fenech R, Gatt RM, Salek MS, Finlay AY. The Dermatology Life Quality Index 1994-2007: a comprehensive review of validation data and clinical results. Br J Dermatol. 2008; 159:997-1035.

Since 2008, there have been many publications which address various aspects of validation of the DLQI, best accessed by searching PubMed or Google Scholar using the search term 'DLQI'.

To find dermatology publications about quality of life from Cardiff University, you can search ORCA, the University's digital repository of its research outputs, or search PubMed, by using the author search term ‘Finlay AY'.

Although the DLQI is a dermatology-specific measure, it is possible using a mapping technique and ordinal logistic regression to generate quality adjusted life years (QALYs) from DLQI data.

For more information, please see:

Ali FM, Kay R, Finlay AY, Piguet V, Kupfer J, Dalgard F, Salek MS. Mapping of the DLQI scores to EQ-5D utility values using ordinal logistic regression. Qual Life Res 2017; 26(11): 3025-3034.

An Excel spreadsheet is freely available for researchers who may be interested in generating utility values from DLQI data. Please email Dr Faraz Ali for a copy of this spreadsheet at alifm@cardiff.ac.uk.

In this study, the predicted utilities were not assigned by using cut-offs. We calculated probabilities based on the fitted ordinal logistic models for each EQ-5D domain and each outcome within that domain. Using Monte-Carlo simulation, we then obtained outcomes for each subject on each domain and predicted utilities for each subject based on these outcomes.

The mapping algorithm was tested on a European dataset and not specifically on a UK population. Though there may be cultural variation influencing health-related quality of life (HRQoL) and utility responses, we have not tested this specific question in detail.

However, when our model was created using only Italian patients and tested on a Norway population, it performed almost as well as the model derived from the complete dataset.

Our experience suggests that within the European context there is some uniformity of attitudes, cultural norms and responses, as the DLQI has undergone over one hundred validated translations, with many in continental European countries.

As no official European Time Trade-Off (TTO) values exist for EQ-5D health states, we applied the UK TTO values throughout the validation process.

We are not aware of any similar exercise being carried out for any of the other University dermatology quality of life questionnaires.