Priority 11 from the Psoriatic Arthritis PSP

UNCERTAINTY: What factors or tests predict how well an individual with psoriatic arthritis will improve on a treatment?  (JLA PSP Priority 11)
Overall ranking 11
JLA question ID 0108/11
Explanatory note We do not fully understand why some people with psoriatic arthritis are suited to particular treatment and others may not be. Therefore, this question aims to generate evidence to help predict the best treatments for an individual living with psoriatic arthritis(‘the right drug, for the right person, at the right time’). This can be referred to as personalised medicine. It is unclear if someone's age, current investigations, or the therapy's safety profile predicts how they will respond to treatment. These are examples of uncertainties reflecting these questions: How should we best tailor treatments to individuals? Why do some people with psoriatic arthritis react to therapy and others don't? How can we identify which medications that are suitable for a patient? 
Evidence

This question has been partially addressed in the evidence base from the following systematic reviews:
Shan, 2019. Obesity hampered the effect of anti-TNF agents, but not those of abatacept and tocilizumab, suggesting that a personalized treatment strategy should be considered for obese patients with inflammatory diseases https://pubmed.ncbi.nlm.nih.gov/29635017/
Gupta, 2021. The most prevalent comorbiditiesin PsA were hypertension (pooled prevalence 34%), metabolic syndrome (29%), obesity (27%), hyperlipidaemia (24%) and any cardiovascular diseases (19%). Eleven studies consistently showed higher prevalence of comorbidities in PsA than controls. Five studies showed that comorbid patients had more severe disease, poorer quality of life, and increased discontinuation of treatment. Comorbidities, particularly cardiometabolic disorders, were highly prevalent in PsA and more common than in healthy controls. Comorbidities were associated with adverse disease features, but more research is needed on their impact on longitudinal outcomes such as treatment response, work productivity and mortality https://pubmed.ncbi.nlm.nih.gov/33423070/
Machado, 2020. From this systematic review, none of the selected scales have had content validation, even though the FACIT was validated in patients with psoriatic arthritis. Validation studies in specific disorders are warranted https://pubmed.ncbi.nlm.nih.gov/33301180/
Singh, 2018. Obesity is an under-reported predictor of inferior response to anti-TNF agents in patients with select immune-mediated inflammatory diseases. A thorough evaluation of obesity as an effect modifier in clinical trials is warranted, and intentional weight loss may serve as adjunctive treatment in patients with obesity failing anti-TNF therapy https://pubmed.ncbi.nlm.nih.gov/30499259/
Mahil, 2019. Limited evidence indicates that weight loss can improve pre-existing psoriasis and PsA, and prevent the onset of psoriasis in obese individuals. Together with the National Institute for Health and Care Excellence obesity guidance, this informed a local obesity screening and management pathway, providing multidisciplinary weight loss interventions https://pubmed.ncbi.nlm.nih.gov/30729517/
Canete, 2021. The prevalence and impact of medical comorbidity on patient reported outcomes are very high in patients with PsA. Patients with a higher number of comorbidities and/or more severe comorbidities reported worse impacts of their disease on function, patient's global assessment, pain, fatigue, work disability and quality of life. Specifically, fibromyalgia function, quality of sleep and quality of life; anxiety and depression had a negative impact on function and fatigue. Metabolic syndrome had a negative impact on BASDAI, function, quality of life. Obesity had a negative impact on function and pain; smoking (current and ex-smokers) had a negative impact on pain, function, fatigue, quality of life and overall health; alcohol intake had a negative impact on pain, function, fatigue, quality of life and overall health https://pubmed.ncbi.nlm.nih.gov/32270447/
Gratacos, 2019. To update the study of the association between obesity and treatment response in psoriatic arthritis. Concludes, there seems to be a greater risk of withdrawal of treatment due to inefficacy and difficulty in achieving remission in patients with psoriatic arthritis if they are obese https://pubmed.ncbi.nlm.nih.gov/31708450/
Health Research Classification System category Inflammatory and immune system
Extra information provided by this PSP
Original uncertainty examples Can we predict which patients with psoriatic arthritis will respond to which treatment? 
Submitted by 22 uncertainties submitted
PSP information
PSP unique ID 0108
PSP name Psoriatic Arthritis
Total number of uncertainties identified by this PSP. 46  (To see a full list of all uncertainties identified, please see the detailed spreadsheet held on the JLA website)
Date of priority setting workshop 12 July 2021