PSORIATIC ARTHRITIS: RECENT ADVANCES IN PATHOGENESIS AND TREATMENT

A randomized placebo-controlled trial of methotrexate in psoriatic arthritis

Objective. MTX is widely used to treat synovitis in PsA without supporting trial evidence. The aim of our study was to test the value of MTX in the first large randomized placebo-controlled trial (RCT) in PsA.

Methods. A 6-month double-blind RCT compared MTX (15 mg/week) with placebo in active PsA. The primary outcome was PsA response criteria (PsARC). Other outcomes included ACR20, DAS-28 and their individual components. Missing data were imputed using multiple imputation methods. Treatments were compared using logistic regression analysis (adjusted for age, sex, disease duration and, where appropriate, individual baseline scores).

Results. Four hundred and sixty-two patients were screened and 221 recruited. One hundred and nine patients received MTX and 112 received placebo. Forty-four patients were lost to follow-up (21 MTX, 23 placebo). Twenty-six patients discontinued treatment (14 MTX, 12 placebo). Comparing MTX with placebo in all randomized patients at 6 months showed no significant effect on PsARC [odds ratio (OR) 1.77, 95% CI 0.97, 3.23], ACR20 (OR 2.00, 95% CI 0.65, 6.22) or DAS-28 (OR 1.70, 95% CI 0.90, 3.17). There were also no significant treatment effects on tender and swollen joint counts, ESR, CRP, HAQ and pain. The only benefits of MTX were reductions in patient and assessor global scores and skin scores at 6 months (P = 0.03, P < 0.001 and P = 0.02, respectively). There were no unexpected adverse events.

Conclusions. This trial of active PsA found no evidence for MTX improving synovitis and consequently raises questions about its classification as a disease-modifying drug in PsA.

Trial registration. Current Controlled Trials, www.controlled-trials.com, ISRCTN:54376151.

Angiotensin-converting enzyme gene polymorphism in patients with psoriatic arthritis

To investigate the frequency of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism genotypes in adults with psoriatic arthritis (PsA), a heterogeneous chronic disease with autoimmune pathology. ACE gene I/D polymorphism influences the plasma and tissue levels of ACE and has an involvement in inflammatory mechanism. The frequency of ACE gene I/D polymorphism genotypes was determined in 51 adults with PsA from Kuwait, and compared to that in 100 ethnically matched healthy controls using polymerase chain reaction. The distribution of ACE I/D polymorphism and allele frequencies in PsA patients were not significantly different from controls (P > 0.05). Further analyses of PsA patients showed that ACE I/D gene polymorphism was not associated with family history, clinical manifestations, and disease severity. However, the frequency of II genotype was significantly higher in patients with late disease onset than in those with early onset (25 vs. 3%; P = 0.04). No difference was found between the distribution of the ACE genotype in PsA patients and the general population in Kuwait. However, the presence of II genotype may confer susceptibility to the development of late onset PsA.

Estimating the cost and health status consequences of treatment with TNF antagonists in patients with psoriatic arthritis

OBJECTIVES

Tumour necrosis factor (TNF) has been shown to improve the outcomes in patients with psoriatic arthritis (PsA). We estimate the long-term impact on health status of prescribing the TNF antagonist etanercept, and evaluate the cost-effectiveness in a health economic model.

METHODS

The relationship between disability (Health Assessment Questionnaire) and health state utility was explored to estimate the quality-adjusted life years (QALYs) gained from the TNF antagonist etanercept. A model was then used to compare sequences of treatments for PsA after failure of two conventional disease modifying anti-rheumatic drugs (DMARDs). One arm commences on etanercept therapy and this is compared with a strategy commencing with combination therapy of methotrexate and ciclosporin and another commencing with leflunomide. Individual patient data from Phase III etanercept trials is used to populate the model supported by published evidence from extensive literature searches. By incorporating a life table specific for a PsA population, and using a number of evidence- and expert opinion-based assumptions for disease progression, the model was extended beyond the trial duration to a 10-yr time horizon. Cost offsets were produced by avoiding surgery through delayed progression; drug and monitoring costs were also modelled.

RESULTS

Over the 10 yrs, modelled etanercept treatment gave 0.82 more QALYs when compared with combination therapy with methotrexate and ciclosporin, and 0.65 more QALYs in comparison with leflunomide. This equates to a central estimate for the cost per QALY of pound28 189 and pound28 189 for ciclosporin and leflunomide, respectively. Sensitivity analyses demonstrated this could vary by as much as +/-28%.

CONCLUSIONS

With limited data currently available, the potential cost-effectiveness of etanercept in DMARD failures for adults with PsA appears encouraging. The result for other TNF antagonists will depend on how their relative efficacy and drug price compares with etanercept. A number of limitations are described and priorities for further research suggested.

The spondylarthropathies: classification and diagnosis. Do we need new terminologies?

The present classification of a number of arthropathies linked to the B27 antigen under the term spondylarthropathy emphasises the frequent familial aggregation and clustering during follow-up of these diseases. This article is an attempt to review the progress elicited by the introduction of classification criteria for spondylarthropathy and the limitations of the concept. In particular, we address the continued need for better understanding of aetiology and pathogenesis. This makes it likely that we will need new classifications in the future and that this will evolve along with improvements in disease understanding. Working classifications that include the infectious triggers and features of the host response might be useful to guide new approaches.

Methotrexate use in psoriasis and psoriatic arthritis

Methotrexate is an extremely effective drug in the treatment of psoriasis and psoriatic arthritis. In addition, it possesses a very high benefit-to-toxicity ratio compared with other therapies and immunosuppressive agents used in these disorders. Fortunately, most adverse events related to methotrexate are mild, but serious and life-threatening reactions, particularly liver toxicity, may occur. Careful monitoring is essential to prevent most undesirable side effects.

Psoriatic arthritis

Despite the fact that psoriatic arthritis has been recognized as an entity for almost five decades, there are still no valid criteria for either its diagnosis or classification. Several sets of criteria have been proposed but none was studied. None the less, investigators have been able to study the condition and describe its unique features and its natural course and prognosis. However, in order to facilitate further studies, it would be worthwhile to develop an internationally accepted and validated set of criteria, both for the diagnosis and classification of the disease, as well as for the assessment of damage. These criteria would help set up appropriate therapeutic trials in this condition as well.

Laboratory findings and pathology of psoriatic arthritis

Over recent years there has been a great deal of interest in the immunology, molecular biology and pathology of psoriasis and PsA. The pathogenetic mechanisms in PsA are less well understood than those described for psoriasis. There are almost certainly genetic and immune components. What is not clear is whether there is a primary immune defect or whether unknown stimuli lead to the recruitment of the immune system and establishment of the disease; nor is it absolutely clear whether PsA is an extension of psoriasis in certain prone individuals. Vascular abnormalities are the earliest histopathological changes to occur in the psoriatic plaque and are also prominent in the psoriatic synovium. Espinoza et al (1982) have suggested there may be a primary vascular defect in PsA. The fact that vascular changes occur before infiltration of immunocompetent cells and are the first changes to resolve with treatment of psoriasis is likely to be significant. Abnormalities in the cellular kinetics and growth factor sensitivity of keratinocytes, fibroblasts and synoviocytes have been highlighted previously. The ability of these cells to produce growth factors and express HLA class II antigens demonstrates the potential for them to initiate and maintain inflammation. The development and possible increased incidence of PsA in patients with such profound immunodeficiency as acquired immune deficiency syndrome suggests that T helper cells do not play a significant role in the establishment of the disease (Arnett et al, 1991). Previously, many immune changes were described. Unfortunately they are non-specific and do not indicate a fundamental defect or marker of PsA. Vasey (1985) has suggested that insidious exposure to Gram-positive bacteria from the gut, tonsils and psoriatic plaques results in chronically stimulated monocytes, macrophages and dendritic cells. These cells are able to migrate throughout the body. Repeated microtrauma may result in the homing of these cells to sites of injury in the skin, synovium and tendons. Interaction with genetically hyperactive synoviocytes and keratinocytes with concomitant release of growth factors may precipitate early lesions of psoriasis and PsA. This hypothesis needs to be substantiated, but it ties together some of the varying observations seen. Many abnormal laboratory findings have been described. Unfortunately, none of the serological changes is sufficiently specific to be of great help in diagnosis. CRP levels and the ESR remain the best promise as markers of the inflammatory component of the arthritis, while other indicators correlate with certain facets of the disease pathology, but as yet have not found a true niche in the management of PsA.(ABSTRACT TRUNCATED AT 400 WORDS)

Natural history of psoriatic arthritis

Psoriatic arthritis is a distinct form of inflammatory arthritis associated with psoriasis, which exists in a number of clinical presentations. Although a large number of patients have a mild form of arthritis, there is a population who present with a very aggressive, deforming and disabling arthritis. The prognostic factors for the development of this type of arthritis are unclear as yet. Therefore, PsA may not be as benign a condition as previously thought, and the approach to its management should be similar to that for rheumatoid arthritis. Current investigations are in progress to identify the prognostic factors associated with severe disease in PsA. Until the results of these studies are available, all patients should probably be treated more aggressively, and earlier.

Prolactin and immunomodulation

PURPOSE

To review the recent exploration of the role of prolactin in immune function.

MATERIALS AND METHODS

Studies published that were identified through a MEDLINE search as well as through the bibliographies of those articles enumerated.

RESULTS

Both humoral and cell-mediated immunity are compromised in hypophysectomized rats. The reintroduction of prolactin to these animals restores their immune function. Prolactin receptors have been identified on the membranes of white blood cells; furthermore, lymphocytes have been shown to secrete prolactin. Cyclosporin A directly competes with prolactin for binding to these receptors. This may be one mechanism of the immunosuppressive action of cyclosporin A. In addition to diminished levels, prolactin excess may also result in immunocompromise. This has been demonstrated in lactating female and prolactin-treated male rats, as well as hyperprolactinemic humans. Finally, prolactin abnormalities have been described in a number of immunologic disorders, including systemic lupus erythematosus, adjuvant arthritis, experimental allergic encephalomyelitis, and autoimmune uveitis and thyroid disease. Dopaminergic agents that suppress serum prolactin are now being used in clinical trials to treat a number of autoimmune diseases and to prevent rejection in organ transplant recipients.

CONCLUSION

At physiologic levels, prolactin is trophic for lymphocytes. Either too much, or too little, prolactin may be immunosuppressive. Lymphocytes produce a prolactin-like substance. Prolactin may play a role in a number of autoimmune processes.