Lifestyle changes for treating psoriasis

Review question

We wanted to see whether lifestyle changes (e.g. changing diet, exercising, and avoiding smoking and drinking alcohol), alone or combined, were useful in treating psoriasis when compared to no such changes or another psoriasis treatment.

Background

Psoriasis is a long-lasting, inflammatory skin disease; it causes thick, red, itching, and scaling patches. Obesity, drinking, smoking, and an inactive lifestyle can worsen psoriasis. We intended to find out if lifestyle changes can improve psoriasis severity and quality of life, and reduce comorbidities (other conditions occurring alongside a primary condition).

Trial characteristics

We included 10 trials, with 1163 participants, which assessed the effects of low-calorie diet alone; low-calorie diet combined with an exercise programme; a combination of walking exercise and continuous health education; and educational instructions to promote a healthy lifestyle (diet, smoking, and alcohol abstinence). We examined the research evidence up to July 2018.

Non-profit organisations funded four trials, one trial received funding for the education programme from pharmaceutical companies, and the other five trials had no funding or did not report the funding source. All participants were aged at least 18 years (mean age: 43 to 61 years). Where reported, the trials included 656 men and 478 women; all were set in a hospital. In four trials, the participants were limited to people with moderate-to-severe psoriasis. One trial included participants who had initially been treated with oral medicines for moderate-to-severe psoriasis but whose psoriasis had not cleared after four weeks. In four trials, all severities of psoriasis were eligible, but these trials either did not report the participants’ psoriasis severity or only provided average severity scores. One trial included participants with mild psoriasis. Trials compared lifestyle change interventions with usual care (including to continue healthy eating), information only, no treatment, or medical treatment alone. Treatment was given for between 12 weeks to three years.

Key results

The following results are based on obese participants and compare lifestyle change interventions (low-calorie diet) to usual care. A low-calorie diet may reduce the severity of psoriasis (when assessed as the proportion of participants achieving at least 75% improvement from the start of treatment in the Psoriasis Area and Severity Index (PASI 75), a widely used tool for the measurement of psoriasis severity) (low-quality evidence) and probably improves quality of life (moderate-quality evidence). Participants on a low-calorie diet may be more likely to stick to treatment (treatment adherence), but treatment effects vary so it is possible that it may make little or no difference (low-quality evidence). A low-calorie diet probably improves BMI (body mass index: a healthy weight calculator) (moderate-quality evidence). The trials did not say how long they treated participants before they stopped dieting (time to relapse).

The following results are based on obese participants and compare lifestyle change interventions (low-calorie diet plus an exercise programme) to weight-loss information aimed at improving psoriasis. A low-calorie diet plus an exercise programme probably results in a greater reduction in the severity of psoriasis (based on PASI 75), but the effects of this treatment vary, so it is possible that it may make little or no difference. There is probably no difference in treatment adherence between the two groups; however, a low-calorie diet plus exercise programme probably improves BMI reduction (all outcomes based on moderate-quality evidence). Trials did not report quality of life or time to relapse.

Only two trials in this review assessed side effects. In one trial side effects were caused by an additional therapy given to both groups of participants (they were not caused by the dietary treatment). The other trial, which compared two dietary treatments to no treatment, did not observe any side effects. Generally, participants complied with the assessed lifestyle changes successfully.

We found no trials on alcohol abstinence or smoking cessation.

Quality of the evidence

The quality of evidence was moderate to low for the outcomes 'Severity of psoriasis' and 'Adherence to the intervention' and moderate for 'Reduction in comorbidities: change in Body Mass Index (BMI)'. Quality of life, measured in only one of the two key comparisons, was based on moderate-quality evidence. Trial limitations included participants knowing which treatment they were receiving and large number of participants withdrawing from trials.

Authors' conclusions: 

Dietary intervention may reduce the severity of psoriasis (low-quality evidence) and probably improves quality of life and reduces BMI (moderate-quality evidence) in obese people when compared with usual care, while combined dietary intervention and exercise programme probably improves psoriasis severity and BMI when compared with information only (moderate-quality evidence). None of the trials measured quality of life.

We did not detect a clear difference in treatment adherence between those in the combined dietary intervention and exercise programme group and those given information only (moderate-quality evidence). Adherence may be improved through dietary intervention compared with usual care (low-quality evidence). Participants generally adhered well to the lifestyle interventions assessed in the review.

No trials assessed the time to relapse. Trial limitations included unblinded participants and high dropout rate.

Future trials should reduce dropouts and include comprehensive outcome measures; they should examine whether dietary intervention with or without an exercise programme is effective in non-obese people with psoriasis, whether an additional exercise programme is more effective than dietary intervention alone, whether the time to relapse prolongs in people who receive dietary intervention with or without exercise programme, and whether smoking cessation and alcohol abstinence are effective in treating psoriasis.

Read the full abstract...
Background: 

Psoriasis is an inflammatory skin disease that presents with itching, red, scaling plaques; its worsening has been associated with obesity, drinking, smoking, lack of sleep, and a sedentary lifestyle. Lifestyle changes may improve psoriasis.

Objectives: 

To assess the effects of lifestyle changes for psoriasis, including weight reduction, alcohol abstinence, smoking cessation, dietary modification, exercise, and other lifestyle change interventions.

Search strategy: 

We searched the following databases up to July 2018: the Cochrane Skin Specialised Register, CENTRAL, MEDLINE, Embase, and LILACS. We also searched the China National Knowledge Infrastructure, the Airiti Library, and five trials registers up to July 2018. We checked the references of included trials for further relevant trials, and we asked the authors of the included trials if they were aware of any relevant unpublished data.

Selection criteria: 

We included randomised controlled trials (RCTs) of lifestyle changes (either alone or in combination) for treating psoriasis in people diagnosed by a healthcare professional. Treatment had to be given for at least 12 weeks. Eligible comparisons were no lifestyle changes or another active intervention.

Data collection and analysis: 

We used standard methodological procedures expected by Cochrane. The primary outcome measures were 'Severity of psoriasis' and 'Adherence to the intervention'. Secondary outcomes were 'Quality of life', 'Time to relapse', and 'Reduction in comorbidities'. We used GRADE to assess the quality of the evidence for each outcome.

Main results: 

We included 10 RCTs with 1163 participants (mean age: 43 to 61 years; 656 men and 478 women were reported). Six trials examined the effects of dietary intervention (low-calorie diet) in 499 obese participants (mean age: 44.3 to 61 years; where reported, 395 had moderate-to-severe psoriasis). One trial assessed a combined dietary intervention and exercise programme in 303 obese participants with moderate-to-severe psoriasis who had started a systemic therapy for psoriasis and had not achieved clearance after four weeks of continuous treatment (median age: 53 years). Another trial assessed a walking exercise and continuous health education in 200 participants (mean age: 43.1 years, severity not reported). Finally, two trials included education programmes promoting a healthy lifestyle in 161 participants (aged 18 to 78 years), with one trial on mild psoriasis and the other trial not reporting severity.

Comparisons included information only; no intervention; medical therapy alone; and usual care (such as continuing healthy eating).

All trials were conducted in hospitals and treated participants for between 12 weeks and three years. One trial did not report the treatment period. Seven trials measured the outcomes at the end of treatment and there was no additional follow-up. In two trials, there was follow-up after the treatment ended. Five trials had a high risk of performance bias, and four trials had a high risk of attrition bias.

We found no trials assessing interventions for alcohol abstinence or smoking cessation. No trials assessed time to relapse. Only two trials assessed adverse events; in one trial these were caused by the add-on therapy ciclosporin (given in both groups). The trial comparing two dietary interventions to a no-treatment group observed no adverse events.

The results presented in this abstract are based on trials of obese participants.

Outcomes for dietary interventions versus usual care were measured 24 weeks to six months from baseline. Compared to usual care, dietary intervention (strict caloric restriction) may lead to 75% or greater improvement from baseline in the Psoriasis Area and Severity Index (PASI 75) (risk ratio (RR) 1.66, 95% confidence interval (CI) 1.07 to 2.58; 2 trials, 323 participants; low-quality evidence). Adherence to the intervention may be greater with the dietary intervention than usual care, but the 95% CI indicates that the dietary intervention might also make little or no difference (RR 1.26, 95% CI 0.76 to 2.09; 2 trials, 105 participants; low-quality evidence). Dietary intervention probably achieves a greater improvement in dermatology quality-of-life index (DLQI) score compared to usual care (MD −12.20, 95% CI −13.92 to −10.48; 1 trial, 36 participants; moderate-quality evidence), and probably reduces the BMI compared to usual care (MD −4.65, 95% CI −5.93 to −3.36; 2 trials, 78 participants; moderate-quality evidence).

Outcomes for dietary interventions plus exercise programme were measured 16 weeks from baseline and are based on one trial (303 participants). Compared to information only (on reducing weight to improve psoriasis), combined dietary intervention and exercise programme (dietetic plan and physical activities) probably improves psoriasis severity, but the 95% CI indicates that the intervention might make little or no difference (PASI 75: RR 1.28, 95% CI 0.83 to 1.98). This combined intervention probably results in a greater reduction in BMI (median change −1.10 kg/m², P = 0.002), but there is probably no difference in adherence (RR 0.95, 95% CI 0.89 to 1.01; 137/151 and 145/152 participants adhered in the treatment and control group, respectively). There were no data on quality of life. These outcomes are based on moderate-quality evidence.

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