This was a multicenter prospective observational study carried out in 123 centers throughout Spain (the Evaluation of the Health-Related Quality of Life and Use of Resources in Patients with Moderate-to-Severe Plaque Psoriasis in Spain [VACAP] Study). The study was approved by the ethics committee of Hospital La Princesa in Madrid, Spain. Patients were recruited consecutively at each of the participating centers. The recruitment period was from August 9, 2007, to December 21, 2007, and written informed consent was obtained from all patients prior to their participation in the study. All patients were seen at 2 visits. Demographic data and clinical characteristics, including disease severity and HRQoL variables, were gathered at the first visit, and disease severity and HRQoL were re-evaluated at the 4-month follow-up visit.

A total of 1217 patients were recruited. The inclusion criteria were age 18 years or older and a diagnosis of moderate-to-severe psoriasis. Patients with psoriatic arthritis and those participating in other clinical trials were excluded. For the purpose of this study, 4 criteria were established for the diagnosis of moderate-to-severe psoriasis: (a) a Psoriasis Area and Severity Index (PASI) score equal to or greater than 10, (b) a Physician Global Assessment (PGA) score of 5 or higher, (c) affected body surface area (BSA) greater than 10%, and (d) any clinical indication for systemic treatment.

The following demographic data were recorded: age, weight, educational level, employment status, and smoking history. Psoriasis severity was assessed using 3 different tools: PASI,2,8 PGA, and affected BSA. The PASI evaluates the severity of the psoriasis and the surface area affected.

HRQoL assessment was carried out using 4 different questionnaires: the Dermatology Quality of Life Index (DLQI),20–22 the Psoriasis Disability Index (PDI),23–25 the EuroQol questionnaire (EQ-5D),17–19 and the Short-Form 36 (SF-36).12–16

The DLQI evaluates the impact of dermatological illnesses and their treatment on the well-being of affected patients. It consists of 10 items organized into 6 dimensions: symptoms and feelings, daily activities, leisure, work and school, personal relationships, and treatment. Each item has 4 response options scored from 0 to 3, giving a maximum score of 30. Higher scores indicate a poorer HRQoL.

The PDI questionnaire is composed of 15 items that assess daily activities, work or school, personal relationships, leisure, and the effects of psoriasis treatment; the items refer only to the month prior to administration of the questionnaire. Items are scored from 0 to 3, with a maximum score of 45. Higher scores correspond to a poorer quality of life.

The Short-Form 36 (SF-36) is composed of 36 items that represent 8 different HRQoL dimensions. Two summary scores are obtained: a physical component summary and a mental component summary. The scores range from 0 to 100, with higher scores indicating better health.

The EQ-5D is an instrument designed to measure general health status. It consists of 5 items rated on a 3-point scale with possible responses ranging from “No Problem” to “Extreme Problem” or “Unable to do.” The questionnaire includes a visual analogue scale (a printed picture of a thermometer) on which patients indicate their evaluation of their overall HRQoL. This visual analogue scale is scored from 0 (worst HRQoL) to 100 (best HRQoL).

A database was constructed with the information obtained from the first and second visits. Quantitative data from the questionnaires and scales were analyzed to determine the mean, variance, standard deviation, minimum, maximum, median, 95% confidence interval, and 5% trimmed mean. For qualitative data, the frequency distributions and percentages of the responses were calculated. Means were compared using the t test or nonparametric Mann–Whitney U test, and comparisons of frequency distributions were performed with the Pearson χ2 test or Fisher exact test when a 2×2 contingency table was applicable. The level of statistical significance was set at α=0.05. Lineal regression analysis was used to evaluate the relationship between demographic and clinical characteristics and the HRQoL. The dependent variable was the difference in the PDI between the first and second visits. Independent variables were included in a stepwise, algorithmic manner in the model, with a probability to enter of 0.05 and a probability to leave of 0.10. Categorical variables were transformed into dummy variables. Missing values were excluded from the analyses.

All statistical analyses were performed with the Predictive Analytics Software version 18.0 (PASW Statistics® 18.0).

The mean (SD) age of the patients was 45.1 (13.9) years (15.3% were over 60 years) and 60.8% were men. The mean age of the patients at disease onset was 26.08 (14.19) years, and 76.7% were between 18 and 40 years of age at the time of disease onset. At the time of the study, 68.1% of patients were working and 15.2% were retired (1.5% had retired because of their psoriasis). The demographic characteristics are shown in Table 1.

Based on the assessment of a dermatologist at the first visit, 60.8% of patients were considered to have moderate psoriasis and 39.2% to have severe psoriasis. The mean weight of the patients was 76.8 (15.9) kg, 36.2% were smokers, and 49.6% had relatives with psoriasis, of whom 65.4% were first-degree relatives. The mean number of exacerbations of psoriasis in the previous year was 2.4 (1.9), and 10.5% of patients had chronic rash. The most commonly affected areas were the trunk and upper limbs (83.8% and 90.4%, respectively). In 46.3% of patients there were comorbid conditions associated with the psoriasis, the most frequent of which were metabolic diseases (32.7%), neurological and mental disorders (32.0%), cardiovascular diseases (28.1%), and autoimmune diseases (20.8%). The clinical data of patients participating in the study are summarized in Table 2.

The mean PASI score at the first visit was 13.24 (9.50), and this fell to 5.07 (6.03) at the second visit. In all, 730 patients (60.0%) achieved PASI50 on their second visit, and 500 patients (41.1%) achieved PASI75. The mean PGA score decreased from 4.93 (1.32) at baseline to 3.27 (1.53) at the second visit. On the basis of the BSA criteria for assessing the severity of psoriasis, 89.2% of patients were in the moderate-to-severe psoriasis range at the first visit, and this fell to 51.8% at the second visit. These results are summarized in Table 3.

During the previous year, 95.6% of the patients had received treatment for psoriasis; 35.7% had received biological therapies.

The SF-36 dimensions with the best mean scores at the first visit were physical functioning (83.67 [21.44]), followed by role-emotional (81.33 [23.63]), and role-physical (78.02 [25.97]). The dimensions that showed the greatest improvement between visits were social functioning (increase from 76.14 [25.82] to 83.80 [22.09]), role-physical (increase from 78.02 [25.97] to 83.58 [22.48]), and bodily pain (increase from 67.08 [29.35] to 73.56 [27.96]). These changes were statistically significant (P<.001).

The EQ-5D dimensions with the lowest scores at the first visit were pain (1.57 [0.58]) and anxiety/depression (1.42 [0.56]). The dimensions that showed the greatest improvement at the second visit were pain (1.48 [0.60]) and anxiety/depression (1.35 [0.55]).

The DLQI score fell from 8.97 (7.28) at baseline to 4.76 (5.72) at the second visit. This improvement was reflected in all dimensions, and all the changes were statistically significant (P<.001). The changes in the PDI score were also statistically significant, with a fall from 9.24 (8.76) at baseline to 4.88 (6.66) at the second visit (P<.001). The results of the HRQoL questionnaires are summarized in Table 3.

The results of the multivariate analysis reveal that disease severity and extent (measured by the PASI score) (b=0.405; P<.001) and gender (b=0.075; P=.048) were the most significant factors in determining a patient's quality of life. A summary of the results of the multivariate linear regression is shown in Table 4. The residual plots are shown in Figs. 1 and 2. These plots show that the linear model provides a suitable fit to the data.

Figure 1.

Standardized residual histograma. (aPsoriasis Disability Index scores: visit 2−visit 1).

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Figure 2.

Normal probability–probability plot of regression standardized residuals. aPsoriasis Disability Index scores: visit 2−visit 1.

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The demographic characteristics of the patients in the VACAP study are similar to those reported in other studies on psoriasis patients. The mean age at disease onset was also similar to the age reported in other studies from Spain.3,5,26,27 According to the results obtained in several European countries, psoriasis is most likely to appear between 15 and 30 years of age,4 a finding supported by the results of our study, in which disease onset occurred in this age range in 55.2% of the patients.

Henseler et al.28 proposed that there are 2 different types of psoriasis, based on the age of onset: type I develops before 40 years and type II in patients older than 40 years. Those authors observed that type I psoriasis was associated with HLA-Cw6 and a positive family history of the disease. However, in the current study, only 23.3% of the patients were over 40 years of age at the time of disease onset, and the distribution did not follow the proposed bimodal pattern. We were thus unable to confirm Hensler et al.’s hypothesis.

Several studies report the importance of genetics in the onset of psoriasis.29–33 In the current study, half of the patients stated that they had relatives with psoriasis and, of these, 65.4% were first-degree relatives. This is similar to the findings of other studies5,26 and confirms the importance of genetic factors in an individual's susceptibility to psoriasis.2

The percentage of patients treated with biological therapies was higher than has been observed in other studies, which have reported the use of biologics in approximately 5% of their overall study populations.4,5 In the VACAP study, the prevalence of biological therapies was much higher, at around 36%. These results are a reflection of the major advances that have taken place in the treatment of psoriasis—these therapies, which are indicated for the treatment of patients with moderate-to-severe psoriasis, are associated with a reduction in disease severity and an improvement in the HRQoL.

Assessment by generic HRQoL questionnaires (SF-36, EQ-5D) shows the dimensions most affected in psoriasis patients to be those related to pain and psychological disturbances. Pain is the most common complaint, followed by itching.7 The results of this study confirm that psoriasis impairs the mental health of affected patients.9,34–36 Scores in the disease-specific HRQoL questionnaires (DLQI, PDI) had improved by the second visit, although these scores were already relatively low at baseline. A similar change was detected during the PDI validation study in Spain.25 Those authors observed that their patients had low PDI scores, and highlighted potential, culturally specific issues with the administration of the PDI questionnaire to a Spanish population. In our study, the DLQI also yielded a low mean score at baseline. Ferrandiz et al.27 proposed the need for a new HRQoL questionnaire to improve the sensitivity of quality-of-life assessments in patients with psoriasis. Despite these limitations, the results of the disease-specific questionnaires showed that psoriasis had a significant effect on quality of life, and multivariate analysis confirmed that there was a directly proportional linear relationship between the severity of psoriasis and the degree of impairment of the HRQoL. Patients with severe psoriasis had psychological distress,37,38 a negative body self-image,39 feelings of stigmatization,40 and poorer social interactions39; these factors explained the impairment in the HRQoL.

Independently of the severity of psoriasis, HRQoL was poorer in women than in men. This gender-specific effect has not only been reported in previous publications on psoriasis38,40 but has also been observed in other dermatological diseases such as hand eczema.41 Finzo et al.38 reported that a possible reason for this effect could be that women usually tend report more psychological disturbances than men. The VACAP study confirmed the main findings of other studies, specifically, that psoriasis leads to an impairment in the health-related quality of life. Our results show that a significant improvement in the severity index of the disease is related to an improvement in the health-related quality of life of affected patients.

The authors declare that the procedures followed were in accordance with the regulations of the responsible Ethics Committee and in accordance with those of the World Medical Association and the Helsinki Declaration.

The authors declare that they have followed the protocols of their work centre on the publication of patient data and that no private patient data are disclosed in this article.

All the patients included in the study have received sufficient information and have given their informed consent in writing to participate in that study. The author for correspondence is in possession of this documentation.