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Prevalence of psoriatic arthritis and joint complaints in a large population of Italian patients hospitalised for psoriasis

European Journal of Dermatology. Volume 15, Number 4, 279-83, July-August 2005, Clinical report

Summary

Author(s) : Paolo Gisondi, Giampiero Girolomoni, Francesca Sampogna, Stefano Tabolli, Damiano Abeni , Istituto Dermopatico dell’Immacolata, IRCCS, Via Monti di Creta 104, 00167 Roma, Italy., Department of Biomedical and Surgical Sciences, Section of Dermatology, University of Verona, 37126 Verona, Italy.

Summary : We investigated the prevalence of psoriatic arthritis and joint complaints in a large population of Italian patients hospitalised for psoriasis. A total of 936 patients were evaluated for psoriatic arthritis according to the European Spondyloarthropathy Study Group (ESSG) criteria. They were visited by a dermatologist who evaluated specific joint signs and symptoms (i.e. arthralgia, stiffness, swelling, ankylosis, paresthesia) and assessed skin disease severity. Information on socio-demographic variables and other factors of clinical interest was also collected. Seventy-one patients (7.7% of the sample) had psoriatic arthritis (PsA). Overall, 90% of patients with PsA referred arthralgia, 70.4% stiffness, 67.7% swelling, 25.4% paresthesia, and 23.9% had ankylosis. However, among patients with plaque psoriasis who did not fulfil the criteria for PsA, 12.3% referred paresthesias, 7% arthralgia, 4.2% stiffness, 3.7% swelling, and 1.2% had ankylosis. Among 114 patients referring arthralgia, 42 (39.6%) did not meet the ESSG criteria for PsA. Therefore, patients with plaque psoriasis refer joint symptoms quite frequently making it difficult to distinguish patients with psoriatic arthritis from patients with joint complaints.

Keywords : diagnostic criteria, joint complaints, prevalence, psoriasis, psoriatic arthritis

ARTICLE

Auteur(s) :, Paolo Gisondi^1,2, Giampiero Girolomoni², Francesca Sampogna¹, Stefano Tabolli¹, Damiano Abeni^1,*

¹Istituto Dermopatico dell’Immacolata, IRCCS, Via Monti di Creta 104, 00167 Roma, Italy.
²Department of Biomedical and Surgical Sciences, Section of Dermatology, University of Verona, 37126 Verona, Italy

accepté le 11 Mars 2005

Psoriatic arthritis (PsA) is a chronic inflammatory arthropathy closely associated with psoriasis [1]. The European Spondyloarthropathy Study Group (ESSG) has included PsA in the group of seronegative spondyloarthropathies together with ankylosing spondylitis, arthritis of inflammatory bowel disease and Reiter disease, and has also introduced currently used classification criteria [2]. PsA may be a severe and disabling disease, in which early diagnosis is crucial to introduce a disease-modifying therapy. Different data have been reported on the prevalence of PsA in patients with psoriasis, ranging from 6.2% to 34.4% in different studies [3-10]. In the USA, a recent National Psoriasis Foundation survey reported that approximately 23% of people who have psoriasis have PsA [11]. However, the general consensus is that prevalence ranges from 7 to 10% [12-15]. It is conceivable that discrepancies in prevalence estimates could depend on applying different diagnostic criteria, different sampling of patients, as well as real variations in the prevalence and expression of PsA in different populations. In most cases, PsA develops after skin disease making the dermatologist the physician who should recognise and treat early-phase PsA. However, patients with plaque psoriasis may complain of musculoskeletal symptoms not necessarily related to PsA, similarly to people without psoriasis [16]. Therefore, there is a need to distinguish patients with PsA from those with psoriasis and joint complaints in order to accurately diagnose PsA. The objective of our study was to estimate the prevalence of PsA, and joint signs and symptoms in a large population of Italian patients with skin psoriasis.

Materials and methods

Study population

This study was part of a wide clinical and epidemiological study on psoriasis, the Italian Multipurpose Psoriasis Research on Vital Experiences (IMPROVE) study [17]. Patients were recruited between February 21^st 2000 and February 19^th 2002 at the inpatient wards of our Institute. During the study period a wide range of psoriasis patients were hospitalised. The indications for the hospitalisation of the patients were mainly the severity of psoriasis and PsA requiring close assistance. However, hospitalisation was also provided to patients with moderate clinical disease severity in order to supply them with treatment and diagnostic procedures that may not be available in their regions of residence (e.g., phototherapy, magnetic resonance imaging). The study was approved by the Institutional Review Board. Patients admitted with a diagnosis of psoriasis were contacted by our dermatologists, who verified the diagnosis and the inclusion criteria (i.e., 18 years of age or more, absence of any severe mental illness, at least 5 years of education, ability to read Italian, first hospitalisation for psoriasis since the date of the beginning of the study), and explained the purposes and methods of the study to the patients. All eligible patients who gave their written informed consent were recruited in the study. In this analysis we considered patients with PsA and patients with chronic plaque psoriasis in order to obtain meaningful comparisons between patients with PsA and a homogeneous and sufficiently large group of psoriasis patients.

Assessment of PsA and joint complaints

PsA belongs to a group of inflammatory arthritic conditions called the spondyloarthropathies, which also include reactive arthritis, ankylosing spondylitis and enteropathic arthropathy. This group shares some characteristics that have been defined in the ESSG criteria [2]. According to these criteria we classified a psoriatic patient as affected by PsA when he showed asymmetric or predominantly lower extremity synovitis or inflammatory spinal pain plus enthesopathy, or sacroiliitis (as determined from radiography of the pelvic region). We formally investigated prevalence of the following articular signs and symptoms: arthralgia, stiffness, swelling, ankylosis, paresthesia. Our working definition of arthralgia was pain in any joint for more than 2 consecutive weeks in the last year; joint stiffness was the lack of easy mobility of a joint especially after periods of inactivity (for example, sleeping or prolonged sitting), lasting for about 30 minutes or more and improved with mild activity. Joint swelling was defined as actual or referred persistent (more than 1 week) tumefaction of any joints; and ankylosis as immobility and consolidation of a joint. Paresthesia was a burning, prickling and/or tingling sensation in one or more joints.

Measure of clinical severity of skin psoriasis

The Psoriasis Area and Severity Index (PASI) scores were calculated using the formula originally proposed by Fredriksson et al. [18]. The clinical severity using the PASI was assessed during the first hours of hospitalisation, before any medication was administered. Body surface area (BSA) was measured using the palm or the rule of nines methods. Plaque psoriasis was defined as localised when it affected less than 10% and generalised when it involved more than 10% of the total BSA. Patients completed the self-administered PASI (SAPASI). This is a structured, validated instrument measuring the clinical severity of psoriasis based on the evaluation by the patient himself of the affected area and average level of lesion erythema, desquamation, and induration. SAPASI has been shown to have an excellent acceptability by the patients and very close correlation with PASI [19]. Information on socio-demographic variables, clinical history, and other factors of clinical interest, including gender, age, clinical type and location of the disease, personal and family history of psoriasis and psoriatic arthritis, smoking habits, and body mass index (BMI), was also collected and recorded.

Statistical analysis

Differences in the prevalence of the considered symptoms observed in the levels of each clinical and socio-demographic variable were tested using chi-squared statistics. For PASI and SAPASI score differences between the clinical types of psoriasis were tested using the non-parametric Kruskal-Wallis test. All statistical analyses were run under SPSS, version 9.0 for Windows [20]. Differences were considered significant when the P-value was < 0.05.

Results

During the study period, 1 721 patients with psoriasis were hospitalised at our Institute. Of them, 269 were not contacted, 121 refused to participate, and 395 where excluded because they did not meet the inclusion criteria. Thus, the total sample included 936 patients, but the clinical type was not recorded for 13 (1.4%) of them. Among the 923 patients for whom the clinical classification has been recorded, 455 (49.3%) were classified as having generalised chronic plaque psoriasis; 147 (15.9%) had localised plaque psoriasis; 118 (12.8%) had guttate psoriasis; 69 (7.5%) had palmoplantar psoriasis; 29 (3.2%) had either localised or generalised pustular psoriasis; 34 (3.8%) had other clinical types (including inverse, erythrodermic). The remaining 71 patients (7.7%) (95% confidence interval [C.I.] 6.0-9.5%) had PsA, according to the ESSG diagnostic criteria. Of these 71 patients affected by PsA, 66% presented generalised plaque psoriasis, 28% localised plaque psoriasis and 5% pustular psoriasis of the palms and soles (Barber), and 1% inverse psoriasis.

In table 1( Table 1 ), we compared demographic and clinical characteristics of patients with PsA with those of plaque psoriasis patients, subdivided into localised and generalised. Prevalence of PsA was significantly higher in females (9.4%, 95% C.I. 6.7-12.9) compared to males (6.6%, 95% C.I. 4.7-9.0). As for age groups, prevalence of PsA was lower in patients less than 40 years old (5.2%, 95% C.I. 3.3-8.2) but then similar in the other two age groups (9.2%, 95% C.I. 6.4-12.9 and 9.5%, 95% C.I. 6.1-14.3, among 40-59 and > 60 years old, respectively). Frequency of positive family history for psoriasis was approximately the same in PsA (49.3%) and generalised plaque psoriasis (51.4%), with lower frequency in localised forms (36.1%). A positive family history for PsA was more frequent in PsA than in plaque psoriasis, but the difference was not statistically significant. Frequency of smoking both during the study period and at onset of disease was lower in PsA compared to plaque psoriasis with P-values very near to the limit of statistical significance (p = 0.056 and p = 0.066, respectively). No differences in BMI between the three groups were noted. Median PASI score was 5.8 for localised plaque psoriasis, 8.2 for generalised plaque psoriasis, and 7.9 for PsA. Median SAPASI score was 7.9 for localised plaque psoriasis, 14.9 for generalised plaque psoriasis, and 12.3 for PsA. All patients enrolled received a topical therapy for psoriasis during hospitalisation. The proportion of patients with a PASI score > 10, requiring systemic treatment for psoriasis, was 24.1%. Almost 90% of patients with PsA received a specific treatment for arthritis.

Overall 90.1% of patients with PsA referred arthralgia and 70.4% stiffness, 67.7% referred or had joint swelling, 23.9% had ankylosis and 25.4% referred paresthesia (table 2( Table 2 )).

Among patients with plaque psoriasis (i.e. either localised or generalised type) and without PsA, 7.0% referred arthralgia, 4.2% stiffness, 3.7% referred or had joint swelling, 1.2% had ankylosis and 12.3% referred paresthesia. Differences between localised and generalised plaque psoriasis were minimal and not statistically significant. When considering the total number of patients referring arthralgia (n = 106), 42 of them (39.6%) did not meet the criteria for PsA. Among patients complaining of other joint signs and symptoms, the proportion of patients with plaque psoriasis not meeting the criteria for PsA was: stiffness 33.3%; swelling 31.4%; ankylosis 29.2%; and paresthesia 80.4%.
Table 1 Characteristics of the study population

		Plaque, localised		Plaque, generalised		Psoriatic arthritis
		n	%	n	%	n	%	P-value
Gender	Male	96	65.3	297	65.3	36	50.7
	Female	51	34.7	158	34.7	35	49.3	0.005
Age	18-39 y	64	43.5	171	37.6	19	26.8
	40-59 y	48	32.7	178	39.1	31	43.7
	60+ y	35	23.8	106	23.3	21	29.6	0.169
Familial psoriasis	Yes	53	36.1	233	51.4	35	49.3
	No	94	63.9	220	48.6	36	50.7	0.005
Familial PsA	Yes	35	23.8	108	23.8	23	32.4
	No	112	76.2	345	76.2	48	67.6	0.287
Present smoker	Yes	81	55.9	227	50.3	26	38.2
	No	64	44.1	224	49.7	42	61.8	0.056
Smoker at onset	Yes	89	61.0	256	56.8	30	44.1
	No	57	39.0	195	43.2	38	55.9	0.066
BMI	<= 24.9	68	47.9	171	38.9	30	42.9
	25-29.9	50	35.2	168	38.2	26	37.1
	30+	24	16.9	101	23.0	14	20.0	0.363
Median PASI score		5.8		8.2		7.9
Median SAPASI score		7.9		14.9		12.3

Table 2 Prevalence (%) of articular symptoms and signs in the study population

		Plaque, localised n = 147	Plaque, generalised n = 455	Arthropatic n = 71	Total n = 673
Arthralgia	overall	7.6	6.8	90.1	15.8
	hands	6.2	4.8	73.2	12.4
	feet	2.1	2.4	60.6	8.5
	sacrum	0.0	1.8	39.4	5.4
Stiffness	overall	3.4	4.4	70.4	11.2
	hands	3.4	4.4	57.7	9.8
	feet	1.4	1.1	32.4	4.5
Swelling	overall	3.4	3.7	67.6	10.4
	hands	3.4	3.1	56.3	8.8
	feet	1.4	1.8	35.2	5.2
Ankylosis	overall	0.7	1.3	23.9	3.6
	hands	0.7	1.3	19.7	3.1
	feet	0.0	0.2	5.6	0.7
Paresthesia	overall	9.5	13.2	25.4	13.7

Discussion

In this study we showed that in a single-centre research setting, the prevalence of PsA diagnosed according to the ESSG criteria among patients with psoriasis was 7.7%, with the true prevalence very unlikely to be greater than 10%. On the other hand, joint complaint (i.e. arthralgia, stiffness, swelling, ankylosis and paresthesia) in our sample of patients with chronic plaque psoriasis was as frequent as 17%. The prevalence of PsA in patients with psoriasis has been reported to range greatly in different studies from different countries. Similar prevalences were reported by Shbeeb et al. (6.2%) and by Barisic-Drusko et al. who found that 7.2% of patients with psoriasis vulgaris were diagnosed as having PsA [4, 6]. Zanolli et al. found the prevalence of PsA in their population of 495 patients to be 17% and over 53% of psoriasis patients to have a current or a previous history of arthralgia [7]. Biondi Oriente et al. reported that 21.3% of 646 patients with psoriasis exhibited PsA [8]. Stern found that nearly 40% of 1 285 psoriasis patients suffered from arthralgia, and 20% had been diagnosed as having PsA. Moreover, patients with PsA had more extensive cutaneous disease and more frequently had a family history of PsA [9]. Scarpa et al. found the prevalence of PsA in his population of 180 psoriatic patients as being 34.4% [10]. Salvarani et al. compared the sensitivity and specificity of existing criteria (i.e. Moll and Wright, ESSG, and Amor et al. [21]) in a population of 205 psoriatic patients from Italy. Moll and Wright criteria identified 22% of cases of PsA, ESSG criteria 24%, Amor criteria 24% and overall the 3 criteria identified 31% of patients with PsA [5]. Our observed prevalence of PsA falls in the lower portion of the range of previous estimates, but it is within the range most commonly reported in the textbooks [13, 15, 22, 23], and reviews [12-14]. Such large differences in the estimated prevalence of PsA may be at least in part due to the different research methods (e.g. different diagnostic criteria, questionnaire versus physical examination, dermatological versus rheumatological patient populations).

We showed that the joint signs and symptoms such as arthralgia, stiffness, swelling, ankylosis and paresthesia are very frequent in patients with PsA, but they are also quite common in patients with plaque psoriasis not affected by arthritis. This could suggest that the frequency of PsA could well be overestimated, both by dermatologists and patients, if standardised diagnostic criteria are not applied. It is interesting to note that approximately one third of patients with specific articular signs and symptoms do not have PsA. Thus, when dermatologists consider joint complaints in patients with psoriasis, they have to distinguish PsA from other causes of joint disease, such as rheumatoid arthritis, osteoarthritis, gout, reactive arthritis, ankylosing spondylitis, and inflammatory bowel disease related arthritis. These referred joint complaints could be a disturbing factor in making a diagnosis of PsA. There is still no specific diagnostic test for PsA, but the ESSG classification criteria, Moll and Wright criteria, Amor et al. criteria have been established to standardise the diagnosis of PsA. The ESSG criteria which group PsA with other spondyloarthropathy forms resulted in a sensitivity and a specificity of 87% [2]. The ESSG diagnostic criteria are insensitive in disease of less than 1 year duration and cannot be used to diagnose some patients with an early spondyloarthropathy, e.g. the patient who develops arthritis before psoriatic skin lesions [24]. Whatever classification criteria are applied, there is still no satisfactory definition of PsA, and the criteria may be too specific and thus may fail to represent the full spectrum of disease. The ESSG has developed a set of criteria for the entire group of spondyloarthropathy patients, with the specific intention of including patients with undifferentiated spondyloarthropathy. The ESSG criteria are easy to apply, and give higher priority to clinical than radiological variables, being appropriate also for dermatologists.

There is an obvious need to distinguish patients with PsA from patients with osteoarthritis or patients with psoriasis and joint complaints not related to inflammatory arthritis. Moreover PsA usually develops after skin disease, making the dermatologist the physician who should recognise and treat early-phase PsA in order to prevent the progression of the articular damage. Although plain radiographs are the first line of imaging investigation, dermatologists should be aware that they are often insensitive for demonstrating the early changes of sacroiliitis, an important feature for establishing the early diagnosis of seronegative spondyloarthropathy. In contrast, MR imaging can demonstrate areas that are undergoing active inflammatory changes and enthesitis, supporting the diagnosis of PsA [25]. Ultrasonography has also recently gained wider acceptance and popularity due to the ability of this multiplanar technique to image both bone changes and soft tissue abnormalities, including synovitis [26]. In conclusion, patients with psoriasis referring joint symptoms need a close follow up, either clinical or radiological, in order to detect early changes of PsA, and start treatment that could limit progression of PsA [27].

Acknowledgments

This Study was supported in part by funds from the Italian Ministry of Health, Rome, Italy.

Appendix

The Italian Multipurpose Psoriasis Research on Vital Experiences (IMPROVE) investigators who contributed to this study are: Gianluca Antonelli, Simone Bolli, Rino Cavalieri, Massimo Luca Chinni, Marcello Fazio, Nidia Melo Salcedo, Paola Moscatelli, Paolo Piazza, Orietta Picconi, Maria Antonietta Pilla, Pietro Puddu, Giuseppe Ruggiero, Francesco Sera, Romeo Simoni, Donatella Sordi.

References

1 Ruderman EM, Tambar S. Psoriatic arthritis: prevalence, diagnosis, and review of therapy for the dermatologist. Dermatol Clin 2004; 22: 477-86.

2 Dougados M, Van der Linden S, Juhlin R, Huitfeldt B, Amor B, Calin A, et al. The European Spondylarthropathy Study Group preliminary criteria for the classification of spondylarthropathy. Arthritis Rheum 1991; 34: 1218-27.

3 Alamanos Y, Papadopoulos NG, Voulgari PV, Siozos C, PsychosDN, Tympanidou M, et al. Epidemiology of psoriatic arthritis in northwest Greece, 1982-2001. J Rheumatol 2003; 30: 2641-4.

4 Shbeeb M, Uramoto KM, Gibson LE, O’Fallon WM, Gabriel SE. The epidemiology of psoriatic arthritis in Olmsted County, Minnesota, USA, 1982-1991. J Rheumatol 2000; 27: 1247-50.

5 Salvarani C, Lo Scocco G, Macchioni P, Cremonesi T, Rossi F, Mantovani W, et al. Prevalence of psoriatic arthritis in Italian psoriatic patients. J Rheumatol 1995; 22: 1499-503.

6 Barisic-Drusko V, Dobric I, Pasic A, Paljan D, Jukic Z, Basta-Juzbasic A, et al. Frequency of psoriatic arthritis in general population and among the psoriatics in department of dermatology. Acta Derm Venereol 1994; 186: 107-8.

7 Zanolli MD, Wikle JS. Joint complaints in psoriasis patients. Int J Dermatol 1992; 31: 488-91.

8 Biondi Oriente C, Scarpa R, Pucino A, Oriente P. Psoriasis and psoriatic arthritis. Dermatological and rheumatological co-operative clinical report. Acta Derm Venereol 1989; 146: 69-71.

9 Stern RS. The epidemiology of joint complaints in patients with psoriasis. J Rheumatol 1985; 12: 315-20.

10 Scarpa R, Oriente P, Pucino A, Torella M, Vignone L, Riccio A, et al. Psoriatic arthritis in psoriatic patients. Br J Rheumatol 1984; 23: 246-50.

11 National Psoriasis Foundation web site. New research shows 1 million U.S adults suffer from psoriatic arthritis. Available at: www.psoriasis.org/facts/psa/.

12 Veale DJ, FitzGerald O. Psoriatic arthritis-pathogenesis and epidemiology. Clin Exp Rheumatol 2002; 20: S27-S33.

13 Helliwell PS, Wright V. Psoriatic arthritis: clinical features. In: Klippel JH, Dieppe PA, eds. Rheumatology. London (UK): Mosby, 1998; (21.1-21.8).

14 Espinoza LR, Cuellar ML, Silveira LH. Psoriatic arthritis. Curr Opin Rheumatol 1992; 4: 470-8.

15 Naldi L. Inflammatory skin diseases IV: Psoriasis. In: Williams HC, Strachan D, eds. The challenge of dermato-epidemiology. Boca Raton, Fl: CRC Press, 1997: 175-90.

16 Cimmino MA, Zampogna A, Murroni S, Baruffi S, Alessio G, Maio T, et al. Methodology of an epidemiologic prevalence study in rheumatology: the Chiavari study. Reumatismo 2002; 54: 40-7.

17 Sampogna F, Sera F, Abeni D, IDI Multipurpose Psoriasis Research on Vital Experiences (IMPROVE) Investigators. Measures of clinical severity, quality of life, and psychological distress in patients with psoriasis: a cluster analysis. J Invest Dermatol 2004; 122: 602-7.

18 Fredriksson T. Petterson. Severe psoriasis-oral therapy with a new retinoid. Dermatologica 1978; 157: 238-44.

19 Sampogna F, Sera F, Mazzotti E, Pasquini P, Picardi A, Abeni D, IDI Multipurpose Psoriasis Research on Vital Experiences (IMPROVE) Study Group. Performance of the self-administered psoriasis area and severity index in evaluating clinical and sociodemographic subgroups of patients with psoriasis. Arch Dermatol 2003; 139: 353-8.

20 Norusis MJ. SPSS for windows: professional and advances statistics, release 9.0. Chicago, IL: SPSS Inc., 1999.

21 Amor B, Dougados M, Mijiyawa M. Criteria of the classification of spondylarthropathies. Rev Rheum Mal Osteoartic 1990; 57: 85-9.

22 Franssen MJ, Van de Hoogen FH, Van de Putte LB. Psoriatic arthropathy. In: van de Kerkhof P, ed. Textbook of psoriasis. Oxford: Blackwell Science, 1999.

23 Bennet R. Psoriatic arthritis. In: McCarthy DJ, Koopman WJ, eds. Arthritis and allied conditions. Philadelphia: Lea and Febiger, 1993.

24 Michet CJ. Update on psoriatic arthritis. Int J Dermatol 2004; 43: 479-81.

25 Bennett DL, Ohashi K, El-Khoury GY. Spondyloarthropathies: ankylosing spondylitis and psoriatic arthritis. Radiol Clin North Am 2004; 42: 121-34.

26 Evangelisto A, Wakefield R, Emery P. Imaging in early arthritis. Best Pract Res Clin Rheumatol 2004; 18: 927-43.

27 Stern RS. A promising step forward in psoriasis therapy. JAMA 2003; 290: 3133-5.