Psoriatic arthritis remembering an old enemy in our daily practice

Clinimetry is textually defined as the art of “measuring in the clinic” and it has been the object of study by researchers of yesteryear, who trying to make objective what is subjective (for example, pain) have designed scales or instruments to try to facilitate the understanding and behavior of the diseases in general, demonstrating to be very helpful and evolving extraordinarily in rheumatic diseases.¹

Thankfully, Dr. Daniel Fernández, together with various collaborators, translated into Spanish the ToPAS (Toronto Psoriatic Arthritis Screening Questionnaire) instrument; they, with great methodological rigor, selected this pragmatic tool which allows to identify easily the patient with psoriatic arthritis (PsA).² The authors, after describing the main available instruments, rightly selected the ToPAS questionnaire to guide the dermatologists in the classification and diagnosis of the patients with PsA; however, it is applicable as an aid for any health professional to establish a timely and accurate medical opinion of this disease, whose aggressive behavior and significant affectation of the quality of life of the patients make it equal or more dreadful than rheumatoid arthritis.

The screening of patients with PsA has a very interesting historical background, especially because of their outstanding protagonists, starting from its difficult separation from rheumatoid arthritis, which begins with the discovery – in 1948 – of the rheumatoid factor, until the titanic work of Drs. Moll and Verna Wright, in their detailed form to describe the disease and the various types of joint involvement.^3–5

Other authors who are appreciated by everybody because of their accompaniment in the growth of Colombian rheumatology, Drs. Vasey and Luis Rolan Espinoza, have developed classification criteria for PsA with a very good performance in terms of sensitivity and specificity.⁶ More recently, the CASPAR criteria were developed in a new international collaborative work, in which we had the opportunity to participate under the umbrella of Professor Espinoza, providing patients from his workplace at Louisiana State University (New Orleans, USA). The main advantages of the CASPAR criteria over the criteria of Moll and Wright, as well as over those of Vasey and Espinoza, are a) the inclusion of the family history of psoriasis, and b) the possibility of establishing the diagnosis of PsA in patients who develop inflammatory joint disease even in the presence of a positive rheumatoid factor and symmetric polyarthritis, demonstrating to be the one of greater sensitivity (91%).⁷

Establishing the diagnosis of spondyloarthritis can become a challenge for the physician. In a work published in the Pablo Tobón Uribe Hospital of Medellín it took 5.7±8.6 years to diagnose a group of 71 patients with spondyloarthritis despite being a high-complexity health center.⁸ We cannot ignore the various national and international publications that in this sense the group of the Central Military Hospital of the city of Bogotá, headed by Dr. Rafael Valle, has developed expanding the knowledge of PsA in Colombia,⁹ nor the growing interest of the dermatologists in participating in the multidisciplinary management of rheumatic diseases, with the resulting benefits to the patients, who are our reason for being.

The work of Dr. Fernández, published in the official Journal of the Colombian Association of Rheumatology, explains in detail how the ToPAS instrument was applied initially to 20 patients; each of its variables were previously exposed in terms of understanding, reliability and response time, and its self-administered filling out took 3 min on average.

Once this initial filter was overcome, the questionnaire was applied to 108 patients (65 men, 43 women): 36 (33.3%) with psoriatic arthritis and 72 (66.6%) with psoriasis, demonstrating a sensitivity of 75% and a quite high specificity of 92%, with a positive predictive value of 82% and a negative predictive value of 88%. The Pearson's correlation coefficient showed a high reliability with a value of 0.94 (it should be remembered that values above 0.80 can be considered satisfactory).

The main disadvantage of the work was that the questionnaire could not be applied in the long term, as mentioned by the authors; however, this in no way affected the fulfillment of the objective proposed in the publication.

I encourage this and all efforts aimed at the dissemination, detection and timely treatment of PsA by rheumatologists and not rheumatologists physicians; this will be translated in less disability and, hence, in a higher quality of life for our patients. They are trully very well received.

Conflict of interest

The author declares he does not have any conflict of interest.