Coordinated Management

Introduction

When considering the treatment of psoriatic arthritis (PsA) and psoriasis, the best outcomes are achieved in an approach that involves input from each of the clinicians involved in the patient’s care. This includes the dermatologist and the rheumatologist who are managing the skin and joint disease. Importantly, it should also include the primary care physician, who needs to both recognize the presentation of the disease and monitor both comorbidities and the toxicities that may accompany treatment.

The Role of Primary Care

Given the nature of psoriatic arthritis (PsA) and psoriasis as debilitating systemic diseases and the potential benefit of early diagnosis, primary care physicians will often play a critical role in the early recognition of disease. Cutaneous features are often the first to develop but have a variety of presentations that can be confusing for a practitioner who may not be focusing on skin disease in an examination. While typical plaque psoriasis on the scalp, elbows or knees is often easy to recognize, other presentations, including guttate, palmar-plantar and inverse psoriasis, can be confused with other skin conditions. Those patients whose psoriasis is primarily evident in the nails should be recognized for appropriate treatment options. Primary care physicians need to be able to distinguish psoriasis from other dermatologic conditions and aggressively refer to a dermatologist if the actual diagnosis is not clear. Only when the appropriate diagnosis of skin psoriasis is identified can appropriate therapy be initiated.

Even in cases where the diagnosis of psoriasis is clear to the primary care physician, the musculoskeletal complaints may prove more challenging. In such cases, evaluation by a rheumatologist may identify subtle signs and symptoms of inflammatory arthritis so that PsA may be distinguished from more common osteoarthritis (OA). Enthesitis may pose further challenges; in some cases, chest wall pain or entheseal tenderness may be the only clues to a diagnosis of PsA. Again, a rheumatology consultation can confirm the diagnosis and offer management recommendations. As discussed below, this may be even more critical for joint disease than skin disease, as early diagnosis and intervention may prevent subsequent, irreversible joint damage.

Appropriate care for psoriasis patients requires that the interaction between primary care providers, rheumatologists and dermatologists be a collaborative effort. Given the high incidence of cardiovascular disease, metabolic syndrome and other comorbidities in patients with PsA and psoriasis, the primary care provider plays an important role in managing these issues. While the increase in cardiovascular risk that is uniquely attributable to the psoriatic disease may be somewhat ameliorated by treatment which decreases the activity of systemic inflammation by treating the psoriatic disease, cardiovascular risk remains high in these patients. Primary care providers need to be aware of the additional risk of cardiovascular disease in patients with psoriatic disease and aggressively manage the general risk factors for heart disease including smoking, hyperlipidemia, diabetes, obesity and sedentary lifestyle. At times, it may even be beneficial to incorporate specialists in cardiac risk factor modification for the most effective treatment and management of comorbidities in psoriatic patients.

Gout is another important comorbidity that is potentially extremely debilitating and can be missed by primary providers and dermatologists. When the clinical focus is on identifying the joint changes associated with PsA, the diagnosis of gout can be overlooked, and patients may be undertreated for this painful disease. The higher incidence of gout in psoriasis patients has been attributed to the hyperuricemia associated with increased cell turnover. Since effective treatment of psoriasis may decrease the cell turnover that is implicated in the disease, the risk may be less in patients with well-controlled psoriasis, but gout remains an important diagnosis to consider in any psoriasis patient with acute joint pain and swelling.

Identifying PsA in the Dermatology Office

One of the keys to making the diagnosis of psoriatic arthritis (PsA) in a patient with psoriasis is recognizing the symptoms when they appear. Because the skin disease typically begins years before there is joint involvement, dermatologists are likely to be managing these patients when the arthritis becomes symptomatic, so there must be constant vigilance to recognize them when and if they present. Persistent pain, swelling and particularly stiffness in the joints of a patient with psoriasis should prompt further evaluation. Patients may not always volunteer this information, so it is important to ask about these symptoms as part of the routine visit history, even in patients with relatively limited psoriasis. Dermatologists may not be fully comfortable with the assessment and differential diagnosis in these patients, but any of these symptoms would be an indication for a rheumatologic consultation.

In an effort to address the issue of undiagnosed PsA patients, several screening questionnaires have been developed for use in both the dermatology and primary care office setting (Table 13-1). Each has slightly different features that make them useful in different settings, but all have the same goal: identifying the presence of PsA in a previously undiagnosed patient.

The Toronto Psoriatic Arthritis Screening (ToPAS) questionnaire was developed to screen for the presence of PsA in the general population as well as in patients with known psoriasis. As such, it may be useful in epidemiologic studies as well as in clinical practice. The ToPAS instrument includes questions about pain and stiffness in both peripheral joints and the spine, and it is the only one of the existing questionnaires that includes representative pictures of skin and nail disease. An updated version is being developed that includes pictures of arthritis and dactylitis. This questionnaire has been tested and has performed well in a family practice clinic as well as in a psoriasis clinic and a general dermatology clinic.

The Psoriasis Epidemiology Screening Tool (PEST) is a simple screening tool that includes just five questions and a stick figure that patients can mark up to show areas of joint involvement (Table 13-2). This questionnaire has been shown to be very sensitive for identifying PsA in a psoriasis population (sensitivity 0.94 for identifying PsA according the Classification of Psoriatic Arthritis [CASPAR] criteria), making it a potentially useful screening tool in the dermatology setting to identify patients who may benefit from a rheumatology evaluation.

Finally, the Psoriatic Arthritis Screening and Evaluation (PASE) tool was designed specifically to identify patients in a dermatology office who would benefit from a referral to a rheumatologist. This questionnaire includes 15 questions divided into two subscales assessing symptoms and function. Each question is answered on a scale of 1 to 5, then summed to a maximum of 75. In validation testing, this questionnaire was able to distinguish osteoarthritis (OA) from PsA. This questionnaire also makes it possible to distinguish more severe forms of PsA from less severe disease; the focus on current symptoms, however, means that patients with inactive PsA will score low and may be missed.

All three PsA questionnaires remain primarily research instruments at this time and are not routinely used in clinical care. However, such questionnaires may eventually help to achieve the important goal of identifying psoriasis patients who would benefit from concurrent evaluation and management of their PsA. If nothing else, they might help to stimulate a discussion of joint symptoms with the dermatologist or the primary care provider. The developers of the PASE questionnaire have suggested that it might be administered at the beginning of the visit by a nurse or physician assistant, then used to identify patients who merit a more focused discussion with the dermatologist.

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Co-management of the Patient with PsA and Psoriasis

Once a patient has been identified as having concurrent psoriatic arthritis (PsA) and psoriasis, coordination of rheumatologic and dermatologic care may be useful and, in some cases, essential. Each specialist is uniquely qualified to assess the extent and severity of the disease in their domain, the first step in establishing a treatment plan. In some settings, particularly in academic centers where dermatologists and rheumatologists work in close proximity, this coordination may take place in cooperative clinics that permit patients to be simultaneously evaluated by both specialists. When possible, this type of setting has the added advantage of allowing the dermatologist and the rheumatologist to collaborate on treatment decisions and develop a plan of care that addresses all aspects of the patient’s disease. Even when this practice model is not possible or practical, close and regular communication between the dermatologist and the rheumatologist can achieve many of these same goals.

From a medical perspective, it is important to recognize that the potential sequelae of skin and joint disease are quite different. While, as discussed earlier, skin that has been involved in psoriasis may never completely be normal on a microscopic level, proper treatment will allow for generally normal appearing skin in the future. While specific areas may be more difficult to treat and have longer-term functional and psychological sequelae (eg, psoriasis of the palms and soles or of the genitalia), there should not be any significant permanent scarring. Joint disease, on the other hand, can lead to permanent joint damage and subsequent functional loss, even after the inflammatory component has resolved. The rheumatologist should therefore evaluate the patient for the presence of existing damage and the potential for future damage; both may affect the choice of therapy.

Patient perspectives of disease are also an important component of the evaluation of the patient with PsA and psoriasis, and they play a critical role in treatment decisions. In particular, it is essential to understand how the patient views the various manifestations of their disease and to identify which particular manifestation of disease is most important to them. While ideal management of PsA and psoriasis should address all aspects of the disease, the patient’s perspective may sometimes drive a specific focus.

Some patients are most concerned about the appearance of their skin disease and are less bothered by their joint symptoms; in these patients, a course of treatment that does not adequately address their skin disease (while recognizing the importance of preventing further damage even in joints that may be symptomatically tolerable) will leave them unsatisfied. Other patients may have extensive skin involvement but still be more concerned about joint disease, either because of pain or functional issues. In these patients, physicians may need to resist the temptation to focus therapy on the skin and address the joint involvement as the primary issue. In many cases, the lack of a clear understanding of the patient’s perspective on the disease process may lead to treatment decisions that fail to achieve the goals that are most important to the patient. When dermatologists and rheumatologists work together, they are able to use their own expert experience with skin and joint disease to reach a more complete understanding of the impact of disease in each individual case.

Developing a Treatment Plan

Once a patient has been evaluated and their needs and concerns understood, a comprehensive treatment plan can be designed. At this point, the specific areas of disease involvement and the patient’s point of view regarding this involvement will dictate the choice of therapy. Some therapies, such as topical steroids or light therapy, may be effective for skin involvement but do nothing for joint involvement. Other therapies, such as sulfasalazine, can be useful for joint symptoms but are ineffective for skin disease. Treatments that are effective for peripheral arthritis may not be as effective for other aspects of joint disease, such as enthesitis or axial disease. With this type of information in mind, the physician, either a dermatologist or a rheumatologist or both, can recommend treatment that is tailored to the individual patient.

Group for the Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) has developed an updated set of treatment guidelines based on published evidence that identifies therapies demonstrated to be effective for six broad categories of psoriatic disease involvement (Figure 6-11):

• peripheral arthritis;
• axial arthritis;
• skin;
• nails;
• enthesitis; and
• dactylitis.

Using this approach, the treating physician can select therapies that address all aspects of the patient’s disease. In some cases, such as a patient with peripheral arthritis and active skin disease, it may make less sense to use independent approaches tailored to each manifestation (such as sulfasalazine for joints and Ultraviolet B [UVB] treatments for skin) than to use a seemingly more aggressive approach (such as methotrexate, apremilast or a biologic) that addresses all involved areas. This, again, is where coordination between the dermatologist and the rheumatologist is most helpful; rather than independently addressing their own disease areas, they can coordinate to use a more efficient approach.

A similar approach, the 4-Quadrant Model, categorizes patients according to the degree of joint and skin disease activity (Figure 13-1). Patients with mild skin and joint disease may be easily managed with NSAIDs and topical treatment, such as topical steroids or vitamin D derivatives. Those with both severe skin and joint disease will obviously require systemic therapy, either with methotrexate or a TNF inhibitor. In the other two quadrants — mild skin and severe joint disease, and mild joint with severe skin disease — the selection of therapy is likely to be driven by the more active manifestation. Patient input becomes very important in this model, as the designation of skin disease as severe, for example, may be based as much on the patient’s distress over their skin disease as on the percentage of body surface area involved.

The most effective treatment for psoriatic arthritis (PsA) and psoriasis, then, becomes a coordinated decision involving the patient, the dermatologist and the rheumatologist, with the primary care provider playing a role in the monitoring of toxicity and comorbidities. New therapies are commonly studied to understand for which aspects of psoriatic disease they are effective, so that as new drugs become available, they can be inserted into the treatment algorithm appropriately. Even when a drug is only effective for one aspect of disease, all physicians involved in the care should have some familiarity with its safety profile, so that all can help monitor the patient for toxicities and adverse events.

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