These articles have been accepted for publication in the British Journal of Dermatology and are currently being edited and typeset. Readers should note that articles published below have been fully refereed, but have not been through the copy-editing and proof correction process. WileyBlackwell and the British Association of Dermatologists cannot be held responsible for errors or consequences arising from the use of information contained in these articles; nor do the views and opinions expressed necessarily reflect those of Wiley-Blackwell or the British Association of Dermatologists This article is protected by copyright. All rights reserved. Accepted Date : 02-Jul-2014 Article type : Epidemiology and health services research
Nail Involvement as a Predictor of Concomitant Psoriatic Arthritis in Patients with Psoriasis 1
1
1
1
2
1
A. Langenbruch , M.A. Radtke , M. Krensel , A. Jacobi , K. Reich , M. Augustin
1
IVDP - Institute for Health Services Research in Dermatology and Nursing, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
2
Dermatologikum Hamburg, Hamburg, Germany
corresponding author: Anna Langenbruch IVDP - Institute for Health Services Research in Dermatology and Nursing University Medical Center Hamburg-Eppendorf Martinistr. 52 | D-20246 Hamburg | Germany tel: +49 (0) 40 7410 53 942 | fax: +49 (0) 40 7410 55 348 | email: [email protected]
running head: Nail Involvement Predicts Psoriatic Arthritis
funding sources: This study was supported by research grants from MSD Sharp & Dohme GmbH, Haar, Germany.
conflict-of-interest disclosures: M Augustin, A Jacobi, MA Radtke, K Reich have received funding from MSD Sharp & Dohme for research and were invited speakers and consultants for this company. M Krensel and A Langenbruch have no conflicts of interest to declare.
This article is protected by copyright. All rights reserved. What’s already known about this topic? In dermatological care there is a considerable rate of undiagnosed Psoriatic Arthritis (PsA) among psoriatic patients. Indicators for the detection of PsA are needed for earlier diagnosis and management. The predictive value of clinical and patient reported outcomes for PsA is controversial. Scalp psoriasis and nail disease are postulated as predictors of PsA incidence. What does this study add? Nail psoriasis and inpatient hospital treatment due to psoriasis are the main indicators of concomitant PsA.
Abstract Background Patients with Psoriatic Arthritis (PsA) suffer from increased burden of disease and impairments in quality of life. Early detection and treatment of PsA could contribute to the prevention of clinical and radiologic progression. Objectives Analyse the predictive value of clinical and patient reported outcomes for concomitant PsA in a population based cohort of patients with psoriasis. Methods Retrospective analysis of data from three independent national cross-sectional studies on health care in psoriasis and PsA, conducted in Germany in the years 2005, 2007 and 2008 was performed. N = 3,520 patients with psoriasis were included by dermatologists and n = 2,449 patients via the German patient advocacy group for psoriasis. In all studies psoriasis history, clinical findings, PsA, nail involvement, health care and patient reported outcomes were collected with standardized questionnaires. Results In the regression model on n = 4,146 patients the strongest predictors for concomitant PsA were nail involvement (OR 2.93, 95 % confidence interval (CI) 2.51 - 3.42, p < 0.001) and inpatient hospital treatment (OR 1.63, 95 % CI 1.38 - 1.93, p < 0.001). By contrast, scalp involvement was not a significant predictor.
This article is protected by copyright. All rights reserved. Conclusions Psoriatic patients seen by dermatologists and in patient advocacy groups show clinical indicators of PsA, the most predictive being nail disease. In practice, a comprehensive assessment of clinical findings associated with PsA is needed.
Introduction
Psoriatic arthritis (PsA) is a psoriasis-related chronic, systemic inflammatory condition with typical signs 1
and symptoms both of psoriasis and arthritis . Two independent studies from Germany have resulted in almost similar prevalence of 20.6 % and 19.0 %, respectively, in patients with psoriasis referring to 2,3
dermatologists . Patients with PsA have reduced quality of life and functional capacity compared with psoriatic patients in 4,5
general and - even more - compared with healthy controls . In half of the patients, aggravation of joint 6
damage, which may lead to deformities, has been noted within the first two years of disease . Since joint disease can lead to irreversible bone damage, there is an indication for early detection and treatment of any arthritic affection in psoriasis. For this, an increasing number of dermatologists are dedicated to identify signs and suspicious symptoms for PsA. Vice versa, rheumatologists, who may see markedly different subgroups of patients with PsA should focus on skin lesions associated with PsA. For both groups of physicians, indicators and predictors of PsA permitting early detection of disease are of considerable clinical interest. If validated properly, they may help to identify patients at risk of detoriation. Especially nail involvement, scalp affections and intergluteal/perianal psoriatic lesions are associated with 7,8
a higher likelihood of developing PsA and are therefore regarded as main predictors of PsA . For instance, nail lesions were found in about 40 - 45 % of patients with psoriasis only and in about 87 % of 9,10
patients with PsA
. 11
The nail is just as much a part of the anatomical functional unit of the enthesis as of the skin . The fascia 12
of the enthesis transitions into and is continuous with the nail radix . McGonagle and Tan used MRI of the finger to study the anatomical correlations. Histologically, and with high-resolution MRI, one could see that the extensor tendon which crosses the distal interphalangeal (DIP) joint is connected with the nail 13
radix and matrix via tendinous fibers surrounding the radix . In PsA there is nearly always enthesitis of the DIP joint in the early phase of disease. The inflammatory reaction may be severe, even affecting the nail matrix. This close relationship between the nail, tendinous attachment to the bone, and periosteum may explain why patients with psoriatic arthritis, who typically have inflammatory changes affecting the DIP joint, often develop inflammation of the nail, too. 3
PsA is often prone to be overlooked . Since more than 80 % of patients with PsA present symptoms of 14
psoriasis before developing symptoms of PsA , dermatologists are in a unique position to detect PsA
This article is protected by copyright. All rights reserved. earlier in the disease process through regular, routine screening of psoriasis patients. Therefore, active monitoring of psoriasis patients for signs of joint or arthritic involvement and familiarity with PsA screening, diagnosis and treatment options can help dermatologists to positively impact the clinical course of psoriatic disease. Distinguishing clinical features of PsA include nail involvement in the vast majority of cases. The severity of nail involvement is determined by the site of the inflammatory reaction. If the nail matrix is involved, there may be development of indentations (pitting), leukonychia, red patches in the lunula, and onychodystrophy. Severe nail psoriasis can result in the crumbling of the nail. If the nail bed is affected, typical “oil spots”, splinter hemorrhage, onycholysis, and subungual parakeratosis and hyperkeratosis can be observed.
The main objective of the present analysis was the identification of significant clinical and patient-reported predictors for concomitant psoriatic arthritis in a population based cohort of patients with psoriasis. For this purpose we performed an analysis of data, derived from 3 independent national cross-sectional studies on health care in psoriasis and psoriatic arthritis, conducted in Germany in the years 2005, 2007 and 2008.
The research questions raised were the following: 1. How do patients with PsA, who are treated in dermatology settings, differ from patients without PsA? 2. Which are the strongest predictors of PsA?
Methods Study design This is a retrospective predictor analysis of three psoriasis patient cohorts from three independent national cross-sectional studies on health care in psoriasis and PsA conducted in the years 2005, 2007 3
and 2008. Patients were included by dermatological practices and clinics (PsoHealth 1; 2005 and 2
PsoHealth 2; 2007 ) and via the patient advocacy group “Deutscher Psoriasis Bund (DPB)”, the largest 15
German patient organisation for psoriasis (PsoReal; 2008) . In all three studies a data set on psoriasis history, clinical findings including PsA, nail involvement, health care, and patient reported outcomes were collected with standardized questionnaires filled in by patients and their respective dermatologists (PsoHealth 1 and 2) and exclusively by the patients (PsoReal). Approval of the local ethics committee of the Hamburg Board of Physicians was obtained for all three studies.
This article is protected by copyright. All rights reserved. Centers, patients and outcome measures 3
2
PsoHealth 1 and 2 involved 48 (PsoHealth 1) and 129 (PsoHealth 2) dermatological practices and outpatient clinics that recruited 1,511 (PsoHealth 1) and 2,009 (PsoHealth 2) patients with plaque-type 15
psoriasis. PsoReal was performed with 2,449 members of the DPB suffering from psoriasis. 2,3,16
The prevalence data of PsA of these studies have been published elsewhere
15,17,18
outcomes on quality of health care have also been previously published
. Moreover, the
.
Prospectively assigned indicators to evaluate differences between patients with and without PsA included a variety of epidemiological, patient-reported and clinical parameters: age, sex, years since first diagnosis, health-related quality of life assessed by the Dermatology Life Quality Index (DLQI), health state assessed by EQ-5D Visual analogue scale (EQ-5D VAS), nail involvement, scalp psoriasis, inpatient treatment within the last 5 years due to psoriasis, family history of psoriasis, days off work due to psoriasis in the last 12 months, mean severity of psoriasis assessed by Psoriasis Area and Severity Index (PASI) (PsoHealth 1 and 2 only) (Table 1).
Assessment of psoriatic arthritis PsA was assessed differently in all three studies due to their different designs (Table 2).
Psoriatic patients with probable PsA were classified as group “PsA probable”. Accordingly, patients were included in the group “PsA not probable” only if they did not show any of the symptoms specific for PsA. In accordance with this conservative approach uncertain cases (e. g. confirmation of relevant symptoms without a statement of a physician about a diagnosis or a high probability of PsA) were excluded from analysis.
Statistical analysis All data was described with standard statistical parameters (frequencies for categorical data, mean value, standard deviation for continuous data). The significance tests focused on the comparison of two groups: patients with PsA and those without PsA. Therefore, a combined approach was chosen in order to detect differences between those groups. Most analyses were performed for the combined sample. Separate analyses for samples were conducted if a variable was not included in all studies. Differences between groups with regard to frequencies were analysed by chi-squared tests for independence. Means of two groups were compared by unpaired ttests. In order to take relations of the variables into account, binary logistic regression models were additionally calculated for variables that were assessed in all the studies. Differences with a probability of a type I (alpha) error of ≤ 0.05 were considered as statistically significant in all analyses. It is important to notice the statistical power is high due to the large sample size.
This article is protected by copyright. All rights reserved. Therefore, very weak affects can achieve statistical significance. Hence, effect sizes are important 19
indicators of whether the findings have substantive significance . Therefore, each unpaired t-test was supplemented by effect-size determination (Cohen’s d). According to Cohen, sizes of 0.2, 0.5 and 0.8 20
respectively represent weak, medium and strong effects in unpaired t-tests . Each chi-squared test was also supplemented by effect-size determination (Cohen´s ω). Effect sizes of 0.1, 0.3 and 0.5 are considered small, medium, and large respectively in ω. Missing values were not replaced. Data management and descriptive data analysis was performed using SPSS version 20.0 for Windows.
Results In total, 4,863 patients with psoriasis and verified diagnostic information about the presence or absence of PsA were included with a mean age of 52.9 years; 43 % were female in the combined sample. 30.1 % of those (n = 1,465) were classified as suffering from PsA. The differences in the tested variables between psoriasis patients with PsA and those without PsA were all significant. However, a medium effect size was only found for the variables nail involvement, health state and years since first diagnosis: Patients with PsA had higher frequencies of nail involvement (72.5 % vs. 41.5 %, ω = 0.28) (Table 3). They were also showing a lower health state (EQ-5D VAS = 55.7 ± 22.4 vs. 67.1 ± 20.8, d = 0.53) and more years since first diagnosis of psoriasis (29.4 ± 15.7 vs. 22.4 ± 16.2 years, d = 0.44) (Table 4).
In the regression model the strongest predictors for the presence of PsA were nail involvement (OR 2.93, 95 % confidence interval (CI) 2.51 - 3.42, p < 0.001) and inpatient hospital treatment (OR 1.63, 95 % CI 1.38 - 1.93, p < 0.001) (Table 5). The tested variables explained a variance of 19.7 %.
Discussion
This study was conducted to determine parameters associated with concomitant PsA in a large cohort of psoriatic patients in Germany. The analysis suggests that these patients show typical demographic 21
characteristics of psoriasis as detected by secondary analysis of health insurance data studies from other countries
22,23
as well as by
.
The rationale for the current study was the observation from previous studies that patients with PsA suffer from increased burden of disease, striking impairments in quality of life, a higher loss of working days and a greater consumption of health care resources
24,25
. For this, the early detection and accurate treatment
of PsA most probably will be beneficial to patients, to the payers and to society. In particular, the
This article is protected by copyright. All rights reserved. 26
avoidance of disease progression and irreversible bone damage is a major goal of PsA treatment . Thus, the identification of valid clinical factors predicting PsA in patients with psoriasis of the skin is crucial. To date, studies evaluating these factors have mostly been performed on subgroups of patients identified by 8
rheumatologists . However, a great proportion of patients with psoriasis in Germany is in the care of dermatologists and GPs. Therefore, the current predictor analysis focused on these patients rather than on those filtered by processes leading to rheumatologists. Hence, in terms of external validity the results cannot be generalised to those patients with psoriasis who are not in dermatological treatment. 8
Differently from the prospective study by Wilson at al. no predictors of onset of PsA but of concomitant PsA were analysed. Since there is no long-term data for prospective analysis available, the present study focused on patients investigated in cross-sectional studies of three large German national surveys for psoriasis. Another limitation is the missing differentiation of particular features of nail psoriasis such as pitting and onycholysis. Further studies should explore whether different signs of nail disease show different predictive value. In order to rule out a detection bias due to unclear PsA, all analyses were performed with valid groups: patients presenting a high probability versus those showing a very low probability of PsA. In accordance 8
with the studies by Wilson et al. the presence of nail psoriasis is predictive for PsA in this study. This result could be explained by the Koebner response phenomenon in which microdamage or trauma may be responsible for the skin lesions in psoriasis, analogously, a Koebner response could be responsible for the development of both nail disease and PsA. Indeed, there are microanatomical similarities between the skin and the enthesis: both integrate two different tissue types (in skin, the epidermis and dermis; in the enthesis, bone and fibrocartilage), dissipate stress and promote tissue union 27
by increasing the surface area of contact between the tissues. Furthermore, there is a close functional integration between the nail, the joint and its associated tendons and ligaments, which likely explains the known association between the DIP joint arthritis and nail disease.
28
The nail is intimately linked with the
network of enthesis fibres extending from the extensor tendon and collateral ligament enthesis that anchor the nail directly to the skeleton. Therefore, from a tissue-specific factor it seems that nail dystrophy and PsA are anatomically linked to enthesopathy.
29
Recently, the prevalence of scalp involvement was found to be similar in newly diagnosed PsA patients 30
and those with psoriasis only . This fits to our finding of scalp psoriasis not being a significant predictor of PsA. The contradictory results in literature could be explained by different populations of psoriatic patients with some studies including patients with higher levels of skin involvement and others predominantly in rheumatological care including patients with little skin involvement. With respect to the divergent outcome of the study by Wilson et al. and the present study, it cannot be 8
excluded that scalp involvement is indeed an early indicator for the risk of PsA development , which cannot be detected anymore when PsA is manifest
2,3,16
.
This article is protected by copyright. All rights reserved. In addition to the subgroup comparisons of patients with versus without PsA, a multiple regression analysis was conducted to take relations of the independent variables into account. The tested parameters differing in the subgroup comparisons might support the validity of the predictors. Due to an explained variance of 19.7 % further variables should be analysed to predict PsA in patients with psoriasis. It would be valuable to test the hypothesis raised in this study with prospective data, like those 31,32
being attained by current registries.
In conclusion, five out of nine tested variables significantly contribute to the prediction of PsA. These parameters are helpful for clinical management of patients with psoriasis. They can be easily applied under routine conditions. Thus with just few clinical considerations the detection of PsA and consequently the quality of care of patients with PsA can be improved.
References
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5 6 7 8 9 10 11
12 13
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Simonić E, Peternel S, Stojnić-Soša L et al. Negative and positive life experiences in patients with psoriatic arthritis. Rheumatol Int 2013; 33(6): 1587–93. Radtke MA, Reich K, Blome C et al. Prevalence and clinical features of psoriatic arthritis and joint complaints in 2009 patients with psoriasis: results of a German national survey. J Eur Acad Dermatol Venereol 2009; 23(6): 683–91. Reich K, Krüger K, Mössner R, Augustin M.Epidemiology and clinical pattern of psoriatic arthritis in Germany: a prospective interdisciplinary epidemiological study of 1511 patients with plaque-type psoriasis. Br J Dermatol 2009; 160(5): 1040–7. Zachariae H, Zachariae R, Blomqvist K et al. Quality of life and prevalence of arthritis reported by 5,795 members of the Nordic Psoriasis Associations. Data from the Nordic Quality of Life Study. Acta Derm Venereol 2002; 82(2): 108–13. Taylor WJ. Impact of psoriatic arthritis on the patient: through the lens of the WHO International Classification of Functioning, Health, and Disability. Curr Rheumatol Rep 2012; 14(4): 369–74. Gladman DD. Mortality in psoriatic arthritis. Clin Exp Rheumatol 2008; 26(5 Suppl 51): S62-65. Gelfand JM, Gladman DD, Mease PJ et al. Epidemiology of psoriatic arthritis in the population of the United States. J Am Acad Dermatol 2005; 53(4): 573–7. Wilson FC, Icen M, Crowson CS et al. Incidence and clinical predictors of psoriatic arthritis in patients with psoriasis: a population-based study. Arthritis Rheum 2009; 61(2): 233–9. Gladman DD, Antoni C, Mease P et al. Psoriatic arthritis: epidemiology, clinical features, course, and outcome. Ann Rheum Dis 2005; 64 (Suppl 2): ii14–ii17. Gladman DD, Anhorn KA, Schachter RK, Mervart H.HLA antigens in psoriatic arthritis. J Rheumatol 1986; 13(3): 586–92. Tan AL; Benjamin M, Toumi H et al. The relationship between the extensor tendon enthesitis and the nail in distal interphalangeal joint disease in psoriatic arthritis – a high resolution MRI and histological study. Rheumatology 2007; 46: 253–256. McGonagle D. Enthesitis: an autoinflammatory lesion linking nail and joint involvement in psoriatic disease. J Eur Acad Dermatol Venereol 2009; 23 (Suppl. 1): 9–13. Tan AI, Granger AJ, Tanner SF et al. A high-resolution magnetic resonance imaging study of distal interphalangeal joint arthropahy in psoriatic arthritis and osteoarthritis: are they the same? Arthritis Rheum 2006; 54:1328–33. Armstrong AW, Schupp C, Bebo B.Psoriasis Comorbidities: Results from the National Psoriasis Foundation Surveys 2003 to 2011. Dermatology 2012; 225: 121–6.
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Langenbruch AK, Radtke MA, Augustin M. Quality of psoriasis care from the patients' perspectiveresults of the national health care study PsoReal. Eur J Dermatol 2012; 22(4): 518–24. Radtke MA, Langenbruch AK, Schaefer I et al. Nail psoriasis as a severity indicator: results from the PsoReal study. Patient Relat Outcome Meas 2011; 2: 1–6. Augustin M, Krüger K, Radtke MA et al. Disease severity, quality of life and health care in plaquetype psoriasis: a multicenter cross-sectional study in Germany. Dermatology 2008; 216(4): 366–72. Augustin M, Reich K, Reich C et al. Quality of Psoriasis Care in Germany – Results of the National Study PsoHealth 2007. J Dtsch Dermatol Ges 2008; 6(8): 640–6. Crosby RA, DiClemente RJ, Salazar LF.Analytic Techniques for Observational Research. In: Research Methods in Health Promotion (Crosby RA, DiClemente RJ, Salazar LF, eds). San Francisco: John Wiley & Sons, 2006; 317–46. Cohen J. The statistical power analysis for the behavioral sciences, 2nd ed. Hillsdale, NJ: Erlbaum, 1988. Augustin M, Reich K, Glaeske G et al. Co-morbidity and age-related prevalence of psoriasis: Analysis of health insurance data in Germany. Acta Derm. Venereol. 2010; 90(2): 147–51. Jones SM, Armas JB, Cohen MG et al. Psoriatic arthritis: outcome of disease subsets and relationship of joint disease to nail and skin disease. Br J Rheumatol 1994; 33(9): 834–9. Williamson L, Dalbeth N, Dockerty JL et al. Extended report: nail disease in psoriatic arthritis-clinically important, potentially treatable and often overlooked. Rheumatology 2004; 43(6): 790–4. Mease PJ. Assessing the impact of psoriatic arthritis on patient function and quality of life: lessons learned from other rheumatologic conditions. Semin Arthritis Rheum 2009; 38(4): 320–35. Husted JA, Gladman DD, Farewell VT, Cook RJ.Health-related quality of life of patients with psoriatic arthritis: a comparison with patients with rheumatoid arthritis. Arthritis Rheum. 2001; 45(2): 151–8. Veale DJ. New therapies and new goals for psoriatic arthritis. Arthritis Rheum 2011; 63(4): 874–6. McGonagle D, Tan AL, Benjamin M: The biomechanical link between skin and joint disease in psoriasis and psoriatic arthritis: what every dermatologist needs to know. Ann Rheum Dis 2008; 67: 1–4. McGonagle D, Tan AL, Benjamin M: The nail as a musculoskeletal appendage – implications for an improved understanding of the link between psoriasis and arthritis. Dermatology 2009; 218: 97–102. McGonagle D. Enthesitis: an autoinflammatory lesion linking nail and joint involvement in psoriatic disease. J Eur Acad Dermatol Venereol 2009; 23 (Suppl 1): 9–13. Haroon M, Kirby B, FitzGerald O. High prevalence of psoriatic arthritis in patients with severe psoriasis with suboptimal performance of screening questionnaires. Ann Rheum Dis 2013; 72(5): 736–40. Papp KA, Strober B, Augustin M et al. PSOLAR: design, utility, and preliminary results of a prospective, international, disease-based registry of patients with psoriasis who are receiving, or are candidates for, conventional systemic treatments or biologic agents. J Drugs Dermatol 2012; 11(10): 1210–7. Augustin M, Spehr C, Radtke MA et al. German psoriasis registry PsoBest: objectives, methodology and baseline data. J Dtsch Dermatol Ges 2014; 12(1): 48–57.
This article is protected by copyright. All rights reserved. Tables
Table 1: Variables included as possible predictors for PsA PsoHealth 1 2005 Setting
3
PsoHealth 2 2007
2
PsoReal 2008
15
dermatologist
dermatologist
direct approach to
offices
offices
patients
Age
x
x
x
Sex
x
x
x
Years since first diagnosis of psoriasis
x
x
x
Health-related quality of life (DLQI)
x
x
x
Subjective health state (EQ-5D-VAS)
x
x
x
Nail involvement
x
x
x Psoriasis lesions in
Psoriasis of the head
PASI head
PASI head
yes / no
yes / no
the scalp due to patient documentation in a body scheme
Inpatient treatment in the last 5 years
x
x
x
Patients with family history of psoriasis
x
x
x
Days off work due to psoriasis in the last year
x
x
x
Psoriasis area and severity index (PASI)
x
x
-
3
Reich K et al. 2009
2
Radtke MA et al. 2009
15
Langenbruch AK et al. 2012
This article is protected by copyright. All rights reserved. Table 2: Assessment of PsA in the three studies PsA in ‚PsoHealth 1‘ Recruitment by dermatologists all over Germany.
Diagnostic algorithm: If at least one of the key criteria for joint involvement was met, patients were recommended to consult a rheumatologist. The rheumatological evaluation clarified whether the patient had a PsA or not. PsA in ‚PsoHealth 2‘ Recruitment by dermatologists all over Germany, no rheumatologists involved.
Diagnostic algorithm: If a PsA had been previously confirmed the diagnosis was adopted without further questions. Otherwise: Does the patient suffer from joint complaints? If this item has been affirmed, the dermatologist answered specific questions about history and clinical symptoms relevant for PsA. This list of symptoms followed modified recommendations of the international GRAPPA group (Group for Research and Assessment in Psoriasis and Psoriatic Arthritis, 2007)
24.
The presence of PsA was thus assessed by the dermatologist.
PsA in ‘PsoReal’ Recruitment by postal assessment of German advocacy group members, no rheumatologist involved.
Diagnostic algorithm: Because no medical diagnosis was included in this study, typical symptoms were recorded in a questionnaire derived from study #2. For better validity beyond this assessment, the patients were additionally asked whether the PsA had been diagnosed by a physician.
This article is protected by copyright. All rights reserved.
Table 3: Clinical characteristics and results of the chi-squared test for independence in patients with probable and improbable PsA PsA not probable MV*
n
%
PsA probable n
%
χ
2
df
involvement Site of the psoriasis: head Gender of the patient: female Inpatient treatment (at least once in the last 5 years) Relatives with psoriasis
*missing values **effect size
ω**
value
(n) Site of the psoriasis: nail
p-
1
1,411
41.5
1,062
72.5
392.43
1
.000
0.28
56
2,375
70.5
1,093
75.9
14.45
1
.000
0.06
79
1,398
41.9
659
45.6
5.61
1
.018
0.03
184
606
18.4
484
34.9
149.44
1
.000
0.18
46
1,338
39.7
682
47.3
24.02
1
.000
0.07
This article is protected by copyright. All rights reserved.
Table 4: Descriptive statistics and results of the t-test for independent samples of patients with probable versus improbable psoriatic arthritis (PsA) pooled from three German nationwide cohorts
MV*
PsA not probable
33
n
3365
M±SD
first diagnosis
PsA probable
12
1453
55.2 ± 12.3
PsA not probable
120
3278
22.4 ± 16.2
PsA probable
47
1418
29.4 ± 15.7
PsA not probable
64
3334
6.9 ± 6.2
DLQI
Health state (EQ-5D VAS)
Severity (PASI)*
PsA probable
25
1440
8.6 ± 7.1
PsA not probable
166
3232
67.1 ± 20.8
PsA probable
46
1419
55.7 ± 22.4
PsA not probable
41
2486
10.3 ± 8.8
PsA probable
* assessed in PsoHealth 1 and 2 only ** Missing values (n) ***effect size
11
638
df
-7.92
3,272.03
.000
0.24
-13.92
2,767.07
.000
0.44
-7.97
2,430.04
.000
0.26
16.27
2,533.77
.000
0.53
-3.60
892.34
.000
0.17
value
d´**
51.9 ± 14.7
Age
Years since
p-
t
12.0 ± 10.3
This article is protected by copyright. All rights reserved. Table 5: Logistic regression analysis on variables potentially predicting PsA in a pooled nationwide data set of patients with psoriasis (n = 4,146), Nagelkerkes R-Square = .197 pa
Predictor variable
B
b
SE
value
OR
CI 95 %
Age
.006
.003
.044
1.01
1.00-1.01
Sex
-.144
.076
.060
0.87
0.75-1.01
Time since first diagnosis
.018
.003
.000
1.02
1.01-1.02
DLQI
.007
.006
.271
1.00
0.99-1.02
EQ-5D-VAS
-.018
.002
.000
0.98
0.98-0.99
Scalp psoriasis
.064
.086
.457
1.07
0.90-1.26
Nail involvement
1.07
.079
.000
2.93
2.51-3.42
Inpatient hospital treatment due to psoriasis
.491
.085
.000
1.63
1.38-1.93
Relatives with psoriasis
0.10
.076
.189
1.11
0.95-1.28
a
Age = years; Sex: male = 1, female = 0; Time since first diagnosis: years; DLQI: scale from 0 = minimum to 30 = maximum QoL
impairment; EQ-5D-VAS: scale from 0 = worst health state to 100 = best health state; scalp psoriasis: scalp affected = 1, not affected = 0; nail involvement: nails affected = 1, not affected = 0; inpatient treatment due to psoriasis at least once in the last 5 years: yes = 1, no = 0; relatives with psoriasis yes = 1, no = 0 b
B, regression coefficient; SE, standard error; OR, Odds Ratio (exponentiation of the B coefficient); CI, Confidence Interval
Nail Involvement as a Predictor of Concomitant Psoriatic Arthritis in Patients with Psoriasis 1
1
1
1
2
1
A. Langenbruch , M.A. Radtke , M. Krensel , A. Jacobi , K. Reich , M. Augustin
1
IVDP - Institute for Health Services Research in Dermatology and Nursing, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
2
Dermatologikum Hamburg, Hamburg, Germany
corresponding author: Anna Langenbruch IVDP - Institute for Health Services Research in Dermatology and Nursing University Medical Center Hamburg-Eppendorf Martinistr. 52 | D-20246 Hamburg | Germany tel: +49 (0) 40 7410 53 942 | fax: +49 (0) 40 7410 55 348 | email: [email protected]
running head: Nail Involvement Predicts Psoriatic Arthritis
funding sources: This study was supported by research grants from MSD Sharp & Dohme GmbH, Haar, Germany.
conflict-of-interest disclosures: M Augustin, A Jacobi, MA Radtke, K Reich have received funding from MSD Sharp & Dohme for research and were invited speakers and consultants for this company. M Krensel and A Langenbruch have no conflicts of interest to declare.
This article is protected by copyright. All rights reserved. What’s already known about this topic? In dermatological care there is a considerable rate of undiagnosed Psoriatic Arthritis (PsA) among psoriatic patients. Indicators for the detection of PsA are needed for earlier diagnosis and management. The predictive value of clinical and patient reported outcomes for PsA is controversial. Scalp psoriasis and nail disease are postulated as predictors of PsA incidence. What does this study add? Nail psoriasis and inpatient hospital treatment due to psoriasis are the main indicators of concomitant PsA.
Abstract Background Patients with Psoriatic Arthritis (PsA) suffer from increased burden of disease and impairments in quality of life. Early detection and treatment of PsA could contribute to the prevention of clinical and radiologic progression. Objectives Analyse the predictive value of clinical and patient reported outcomes for concomitant PsA in a population based cohort of patients with psoriasis. Methods Retrospective analysis of data from three independent national cross-sectional studies on health care in psoriasis and PsA, conducted in Germany in the years 2005, 2007 and 2008 was performed. N = 3,520 patients with psoriasis were included by dermatologists and n = 2,449 patients via the German patient advocacy group for psoriasis. In all studies psoriasis history, clinical findings, PsA, nail involvement, health care and patient reported outcomes were collected with standardized questionnaires. Results In the regression model on n = 4,146 patients the strongest predictors for concomitant PsA were nail involvement (OR 2.93, 95 % confidence interval (CI) 2.51 - 3.42, p < 0.001) and inpatient hospital treatment (OR 1.63, 95 % CI 1.38 - 1.93, p < 0.001). By contrast, scalp involvement was not a significant predictor.
This article is protected by copyright. All rights reserved. Conclusions Psoriatic patients seen by dermatologists and in patient advocacy groups show clinical indicators of PsA, the most predictive being nail disease. In practice, a comprehensive assessment of clinical findings associated with PsA is needed.
Introduction
Psoriatic arthritis (PsA) is a psoriasis-related chronic, systemic inflammatory condition with typical signs 1
and symptoms both of psoriasis and arthritis . Two independent studies from Germany have resulted in almost similar prevalence of 20.6 % and 19.0 %, respectively, in patients with psoriasis referring to 2,3
dermatologists . Patients with PsA have reduced quality of life and functional capacity compared with psoriatic patients in 4,5
general and - even more - compared with healthy controls . In half of the patients, aggravation of joint 6
damage, which may lead to deformities, has been noted within the first two years of disease . Since joint disease can lead to irreversible bone damage, there is an indication for early detection and treatment of any arthritic affection in psoriasis. For this, an increasing number of dermatologists are dedicated to identify signs and suspicious symptoms for PsA. Vice versa, rheumatologists, who may see markedly different subgroups of patients with PsA should focus on skin lesions associated with PsA. For both groups of physicians, indicators and predictors of PsA permitting early detection of disease are of considerable clinical interest. If validated properly, they may help to identify patients at risk of detoriation. Especially nail involvement, scalp affections and intergluteal/perianal psoriatic lesions are associated with 7,8
a higher likelihood of developing PsA and are therefore regarded as main predictors of PsA . For instance, nail lesions were found in about 40 - 45 % of patients with psoriasis only and in about 87 % of 9,10
patients with PsA
. 11
The nail is just as much a part of the anatomical functional unit of the enthesis as of the skin . The fascia 12
of the enthesis transitions into and is continuous with the nail radix . McGonagle and Tan used MRI of the finger to study the anatomical correlations. Histologically, and with high-resolution MRI, one could see that the extensor tendon which crosses the distal interphalangeal (DIP) joint is connected with the nail 13
radix and matrix via tendinous fibers surrounding the radix . In PsA there is nearly always enthesitis of the DIP joint in the early phase of disease. The inflammatory reaction may be severe, even affecting the nail matrix. This close relationship between the nail, tendinous attachment to the bone, and periosteum may explain why patients with psoriatic arthritis, who typically have inflammatory changes affecting the DIP joint, often develop inflammation of the nail, too. 3
PsA is often prone to be overlooked . Since more than 80 % of patients with PsA present symptoms of 14
psoriasis before developing symptoms of PsA , dermatologists are in a unique position to detect PsA
This article is protected by copyright. All rights reserved. earlier in the disease process through regular, routine screening of psoriasis patients. Therefore, active monitoring of psoriasis patients for signs of joint or arthritic involvement and familiarity with PsA screening, diagnosis and treatment options can help dermatologists to positively impact the clinical course of psoriatic disease. Distinguishing clinical features of PsA include nail involvement in the vast majority of cases. The severity of nail involvement is determined by the site of the inflammatory reaction. If the nail matrix is involved, there may be development of indentations (pitting), leukonychia, red patches in the lunula, and onychodystrophy. Severe nail psoriasis can result in the crumbling of the nail. If the nail bed is affected, typical “oil spots”, splinter hemorrhage, onycholysis, and subungual parakeratosis and hyperkeratosis can be observed.
The main objective of the present analysis was the identification of significant clinical and patient-reported predictors for concomitant psoriatic arthritis in a population based cohort of patients with psoriasis. For this purpose we performed an analysis of data, derived from 3 independent national cross-sectional studies on health care in psoriasis and psoriatic arthritis, conducted in Germany in the years 2005, 2007 and 2008.
The research questions raised were the following: 1. How do patients with PsA, who are treated in dermatology settings, differ from patients without PsA? 2. Which are the strongest predictors of PsA?
Methods Study design This is a retrospective predictor analysis of three psoriasis patient cohorts from three independent national cross-sectional studies on health care in psoriasis and PsA conducted in the years 2005, 2007 3
and 2008. Patients were included by dermatological practices and clinics (PsoHealth 1; 2005 and 2
PsoHealth 2; 2007 ) and via the patient advocacy group “Deutscher Psoriasis Bund (DPB)”, the largest 15
German patient organisation for psoriasis (PsoReal; 2008) . In all three studies a data set on psoriasis history, clinical findings including PsA, nail involvement, health care, and patient reported outcomes were collected with standardized questionnaires filled in by patients and their respective dermatologists (PsoHealth 1 and 2) and exclusively by the patients (PsoReal). Approval of the local ethics committee of the Hamburg Board of Physicians was obtained for all three studies.
This article is protected by copyright. All rights reserved. Centers, patients and outcome measures 3
2
PsoHealth 1 and 2 involved 48 (PsoHealth 1) and 129 (PsoHealth 2) dermatological practices and outpatient clinics that recruited 1,511 (PsoHealth 1) and 2,009 (PsoHealth 2) patients with plaque-type 15
psoriasis. PsoReal was performed with 2,449 members of the DPB suffering from psoriasis. 2,3,16
The prevalence data of PsA of these studies have been published elsewhere
15,17,18
outcomes on quality of health care have also been previously published
. Moreover, the
.
Prospectively assigned indicators to evaluate differences between patients with and without PsA included a variety of epidemiological, patient-reported and clinical parameters: age, sex, years since first diagnosis, health-related quality of life assessed by the Dermatology Life Quality Index (DLQI), health state assessed by EQ-5D Visual analogue scale (EQ-5D VAS), nail involvement, scalp psoriasis, inpatient treatment within the last 5 years due to psoriasis, family history of psoriasis, days off work due to psoriasis in the last 12 months, mean severity of psoriasis assessed by Psoriasis Area and Severity Index (PASI) (PsoHealth 1 and 2 only) (Table 1).
Assessment of psoriatic arthritis PsA was assessed differently in all three studies due to their different designs (Table 2).
Psoriatic patients with probable PsA were classified as group “PsA probable”. Accordingly, patients were included in the group “PsA not probable” only if they did not show any of the symptoms specific for PsA. In accordance with this conservative approach uncertain cases (e. g. confirmation of relevant symptoms without a statement of a physician about a diagnosis or a high probability of PsA) were excluded from analysis.
Statistical analysis All data was described with standard statistical parameters (frequencies for categorical data, mean value, standard deviation for continuous data). The significance tests focused on the comparison of two groups: patients with PsA and those without PsA. Therefore, a combined approach was chosen in order to detect differences between those groups. Most analyses were performed for the combined sample. Separate analyses for samples were conducted if a variable was not included in all studies. Differences between groups with regard to frequencies were analysed by chi-squared tests for independence. Means of two groups were compared by unpaired ttests. In order to take relations of the variables into account, binary logistic regression models were additionally calculated for variables that were assessed in all the studies. Differences with a probability of a type I (alpha) error of ≤ 0.05 were considered as statistically significant in all analyses. It is important to notice the statistical power is high due to the large sample size.
This article is protected by copyright. All rights reserved. Therefore, very weak affects can achieve statistical significance. Hence, effect sizes are important 19
indicators of whether the findings have substantive significance . Therefore, each unpaired t-test was supplemented by effect-size determination (Cohen’s d). According to Cohen, sizes of 0.2, 0.5 and 0.8 20
respectively represent weak, medium and strong effects in unpaired t-tests . Each chi-squared test was also supplemented by effect-size determination (Cohen´s ω). Effect sizes of 0.1, 0.3 and 0.5 are considered small, medium, and large respectively in ω. Missing values were not replaced. Data management and descriptive data analysis was performed using SPSS version 20.0 for Windows.
Results In total, 4,863 patients with psoriasis and verified diagnostic information about the presence or absence of PsA were included with a mean age of 52.9 years; 43 % were female in the combined sample. 30.1 % of those (n = 1,465) were classified as suffering from PsA. The differences in the tested variables between psoriasis patients with PsA and those without PsA were all significant. However, a medium effect size was only found for the variables nail involvement, health state and years since first diagnosis: Patients with PsA had higher frequencies of nail involvement (72.5 % vs. 41.5 %, ω = 0.28) (Table 3). They were also showing a lower health state (EQ-5D VAS = 55.7 ± 22.4 vs. 67.1 ± 20.8, d = 0.53) and more years since first diagnosis of psoriasis (29.4 ± 15.7 vs. 22.4 ± 16.2 years, d = 0.44) (Table 4).
In the regression model the strongest predictors for the presence of PsA were nail involvement (OR 2.93, 95 % confidence interval (CI) 2.51 - 3.42, p < 0.001) and inpatient hospital treatment (OR 1.63, 95 % CI 1.38 - 1.93, p < 0.001) (Table 5). The tested variables explained a variance of 19.7 %.
Discussion
This study was conducted to determine parameters associated with concomitant PsA in a large cohort of psoriatic patients in Germany. The analysis suggests that these patients show typical demographic 21
characteristics of psoriasis as detected by secondary analysis of health insurance data studies from other countries
22,23
as well as by
.
The rationale for the current study was the observation from previous studies that patients with PsA suffer from increased burden of disease, striking impairments in quality of life, a higher loss of working days and a greater consumption of health care resources
24,25
. For this, the early detection and accurate treatment
of PsA most probably will be beneficial to patients, to the payers and to society. In particular, the
This article is protected by copyright. All rights reserved. 26
avoidance of disease progression and irreversible bone damage is a major goal of PsA treatment . Thus, the identification of valid clinical factors predicting PsA in patients with psoriasis of the skin is crucial. To date, studies evaluating these factors have mostly been performed on subgroups of patients identified by 8
rheumatologists . However, a great proportion of patients with psoriasis in Germany is in the care of dermatologists and GPs. Therefore, the current predictor analysis focused on these patients rather than on those filtered by processes leading to rheumatologists. Hence, in terms of external validity the results cannot be generalised to those patients with psoriasis who are not in dermatological treatment. 8
Differently from the prospective study by Wilson at al. no predictors of onset of PsA but of concomitant PsA were analysed. Since there is no long-term data for prospective analysis available, the present study focused on patients investigated in cross-sectional studies of three large German national surveys for psoriasis. Another limitation is the missing differentiation of particular features of nail psoriasis such as pitting and onycholysis. Further studies should explore whether different signs of nail disease show different predictive value. In order to rule out a detection bias due to unclear PsA, all analyses were performed with valid groups: patients presenting a high probability versus those showing a very low probability of PsA. In accordance 8
with the studies by Wilson et al. the presence of nail psoriasis is predictive for PsA in this study. This result could be explained by the Koebner response phenomenon in which microdamage or trauma may be responsible for the skin lesions in psoriasis, analogously, a Koebner response could be responsible for the development of both nail disease and PsA. Indeed, there are microanatomical similarities between the skin and the enthesis: both integrate two different tissue types (in skin, the epidermis and dermis; in the enthesis, bone and fibrocartilage), dissipate stress and promote tissue union 27
by increasing the surface area of contact between the tissues. Furthermore, there is a close functional integration between the nail, the joint and its associated tendons and ligaments, which likely explains the known association between the DIP joint arthritis and nail disease.
28
The nail is intimately linked with the
network of enthesis fibres extending from the extensor tendon and collateral ligament enthesis that anchor the nail directly to the skeleton. Therefore, from a tissue-specific factor it seems that nail dystrophy and PsA are anatomically linked to enthesopathy.
29
Recently, the prevalence of scalp involvement was found to be similar in newly diagnosed PsA patients 30
and those with psoriasis only . This fits to our finding of scalp psoriasis not being a significant predictor of PsA. The contradictory results in literature could be explained by different populations of psoriatic patients with some studies including patients with higher levels of skin involvement and others predominantly in rheumatological care including patients with little skin involvement. With respect to the divergent outcome of the study by Wilson et al. and the present study, it cannot be 8
excluded that scalp involvement is indeed an early indicator for the risk of PsA development , which cannot be detected anymore when PsA is manifest
2,3,16
.
This article is protected by copyright. All rights reserved. In addition to the subgroup comparisons of patients with versus without PsA, a multiple regression analysis was conducted to take relations of the independent variables into account. The tested parameters differing in the subgroup comparisons might support the validity of the predictors. Due to an explained variance of 19.7 % further variables should be analysed to predict PsA in patients with psoriasis. It would be valuable to test the hypothesis raised in this study with prospective data, like those 31,32
being attained by current registries.
In conclusion, five out of nine tested variables significantly contribute to the prediction of PsA. These parameters are helpful for clinical management of patients with psoriasis. They can be easily applied under routine conditions. Thus with just few clinical considerations the detection of PsA and consequently the quality of care of patients with PsA can be improved.
References
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5 6 7 8 9 10 11
12 13
14
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Langenbruch AK, Radtke MA, Augustin M. Quality of psoriasis care from the patients' perspectiveresults of the national health care study PsoReal. Eur J Dermatol 2012; 22(4): 518–24. Radtke MA, Langenbruch AK, Schaefer I et al. Nail psoriasis as a severity indicator: results from the PsoReal study. Patient Relat Outcome Meas 2011; 2: 1–6. Augustin M, Krüger K, Radtke MA et al. Disease severity, quality of life and health care in plaquetype psoriasis: a multicenter cross-sectional study in Germany. Dermatology 2008; 216(4): 366–72. Augustin M, Reich K, Reich C et al. Quality of Psoriasis Care in Germany – Results of the National Study PsoHealth 2007. J Dtsch Dermatol Ges 2008; 6(8): 640–6. Crosby RA, DiClemente RJ, Salazar LF.Analytic Techniques for Observational Research. In: Research Methods in Health Promotion (Crosby RA, DiClemente RJ, Salazar LF, eds). San Francisco: John Wiley & Sons, 2006; 317–46. Cohen J. The statistical power analysis for the behavioral sciences, 2nd ed. Hillsdale, NJ: Erlbaum, 1988. Augustin M, Reich K, Glaeske G et al. Co-morbidity and age-related prevalence of psoriasis: Analysis of health insurance data in Germany. Acta Derm. Venereol. 2010; 90(2): 147–51. Jones SM, Armas JB, Cohen MG et al. Psoriatic arthritis: outcome of disease subsets and relationship of joint disease to nail and skin disease. Br J Rheumatol 1994; 33(9): 834–9. Williamson L, Dalbeth N, Dockerty JL et al. Extended report: nail disease in psoriatic arthritis-clinically important, potentially treatable and often overlooked. Rheumatology 2004; 43(6): 790–4. Mease PJ. Assessing the impact of psoriatic arthritis on patient function and quality of life: lessons learned from other rheumatologic conditions. Semin Arthritis Rheum 2009; 38(4): 320–35. Husted JA, Gladman DD, Farewell VT, Cook RJ.Health-related quality of life of patients with psoriatic arthritis: a comparison with patients with rheumatoid arthritis. Arthritis Rheum. 2001; 45(2): 151–8. Veale DJ. New therapies and new goals for psoriatic arthritis. Arthritis Rheum 2011; 63(4): 874–6. McGonagle D, Tan AL, Benjamin M: The biomechanical link between skin and joint disease in psoriasis and psoriatic arthritis: what every dermatologist needs to know. Ann Rheum Dis 2008; 67: 1–4. McGonagle D, Tan AL, Benjamin M: The nail as a musculoskeletal appendage – implications for an improved understanding of the link between psoriasis and arthritis. Dermatology 2009; 218: 97–102. McGonagle D. Enthesitis: an autoinflammatory lesion linking nail and joint involvement in psoriatic disease. J Eur Acad Dermatol Venereol 2009; 23 (Suppl 1): 9–13. Haroon M, Kirby B, FitzGerald O. High prevalence of psoriatic arthritis in patients with severe psoriasis with suboptimal performance of screening questionnaires. Ann Rheum Dis 2013; 72(5): 736–40. Papp KA, Strober B, Augustin M et al. PSOLAR: design, utility, and preliminary results of a prospective, international, disease-based registry of patients with psoriasis who are receiving, or are candidates for, conventional systemic treatments or biologic agents. J Drugs Dermatol 2012; 11(10): 1210–7. Augustin M, Spehr C, Radtke MA et al. German psoriasis registry PsoBest: objectives, methodology and baseline data. J Dtsch Dermatol Ges 2014; 12(1): 48–57.
This article is protected by copyright. All rights reserved. Tables
Table 1: Variables included as possible predictors for PsA PsoHealth 1 2005 Setting
3
PsoHealth 2 2007
2
PsoReal 2008
15
dermatologist
dermatologist
direct approach to
offices
offices
patients
Age
x
x
x
Sex
x
x
x
Years since first diagnosis of psoriasis
x
x
x
Health-related quality of life (DLQI)
x
x
x
Subjective health state (EQ-5D-VAS)
x
x
x
Nail involvement
x
x
x Psoriasis lesions in
Psoriasis of the head
PASI head
PASI head
yes / no
yes / no
the scalp due to patient documentation in a body scheme
Inpatient treatment in the last 5 years
x
x
x
Patients with family history of psoriasis
x
x
x
Days off work due to psoriasis in the last year
x
x
x
Psoriasis area and severity index (PASI)
x
x
-
3
Reich K et al. 2009
2
Radtke MA et al. 2009
15
Langenbruch AK et al. 2012
This article is protected by copyright. All rights reserved. Table 2: Assessment of PsA in the three studies PsA in ‚PsoHealth 1‘ Recruitment by dermatologists all over Germany.
Diagnostic algorithm: If at least one of the key criteria for joint involvement was met, patients were recommended to consult a rheumatologist. The rheumatological evaluation clarified whether the patient had a PsA or not. PsA in ‚PsoHealth 2‘ Recruitment by dermatologists all over Germany, no rheumatologists involved.
Diagnostic algorithm: If a PsA had been previously confirmed the diagnosis was adopted without further questions. Otherwise: Does the patient suffer from joint complaints? If this item has been affirmed, the dermatologist answered specific questions about history and clinical symptoms relevant for PsA. This list of symptoms followed modified recommendations of the international GRAPPA group (Group for Research and Assessment in Psoriasis and Psoriatic Arthritis, 2007)
24.
The presence of PsA was thus assessed by the dermatologist.
PsA in ‘PsoReal’ Recruitment by postal assessment of German advocacy group members, no rheumatologist involved.
Diagnostic algorithm: Because no medical diagnosis was included in this study, typical symptoms were recorded in a questionnaire derived from study #2. For better validity beyond this assessment, the patients were additionally asked whether the PsA had been diagnosed by a physician.
This article is protected by copyright. All rights reserved.
Table 3: Clinical characteristics and results of the chi-squared test for independence in patients with probable and improbable PsA PsA not probable MV*
n
%
PsA probable n
%
χ
2
df
involvement Site of the psoriasis: head Gender of the patient: female Inpatient treatment (at least once in the last 5 years) Relatives with psoriasis
*missing values **effect size
ω**
value
(n) Site of the psoriasis: nail
p-
1
1,411
41.5
1,062
72.5
392.43
1
.000
0.28
56
2,375
70.5
1,093
75.9
14.45
1
.000
0.06
79
1,398
41.9
659
45.6
5.61
1
.018
0.03
184
606
18.4
484
34.9
149.44
1
.000
0.18
46
1,338
39.7
682
47.3
24.02
1
.000
0.07
This article is protected by copyright. All rights reserved.
Table 4: Descriptive statistics and results of the t-test for independent samples of patients with probable versus improbable psoriatic arthritis (PsA) pooled from three German nationwide cohorts
MV*
PsA not probable
33
n
3365
M±SD
first diagnosis
PsA probable
12
1453
55.2 ± 12.3
PsA not probable
120
3278
22.4 ± 16.2
PsA probable
47
1418
29.4 ± 15.7
PsA not probable
64
3334
6.9 ± 6.2
DLQI
Health state (EQ-5D VAS)
Severity (PASI)*
PsA probable
25
1440
8.6 ± 7.1
PsA not probable
166
3232
67.1 ± 20.8
PsA probable
46
1419
55.7 ± 22.4
PsA not probable
41
2486
10.3 ± 8.8
PsA probable
* assessed in PsoHealth 1 and 2 only ** Missing values (n) ***effect size
11
638
df
-7.92
3,272.03
.000
0.24
-13.92
2,767.07
.000
0.44
-7.97
2,430.04
.000
0.26
16.27
2,533.77
.000
0.53
-3.60
892.34
.000
0.17
value
d´**
51.9 ± 14.7
Age
Years since
p-
t
12.0 ± 10.3
This article is protected by copyright. All rights reserved. Table 5: Logistic regression analysis on variables potentially predicting PsA in a pooled nationwide data set of patients with psoriasis (n = 4,146), Nagelkerkes R-Square = .197 pa
Predictor variable
B
b
SE
value
OR
CI 95 %
Age
.006
.003
.044
1.01
1.00-1.01
Sex
-.144
.076
.060
0.87
0.75-1.01
Time since first diagnosis
.018
.003
.000
1.02
1.01-1.02
DLQI
.007
.006
.271
1.00
0.99-1.02
EQ-5D-VAS
-.018
.002
.000
0.98
0.98-0.99
Scalp psoriasis
.064
.086
.457
1.07
0.90-1.26
Nail involvement
1.07
.079
.000
2.93
2.51-3.42
Inpatient hospital treatment due to psoriasis
.491
.085
.000
1.63
1.38-1.93
Relatives with psoriasis
0.10
.076
.189
1.11
0.95-1.28
a
Age = years; Sex: male = 1, female = 0; Time since first diagnosis: years; DLQI: scale from 0 = minimum to 30 = maximum QoL
impairment; EQ-5D-VAS: scale from 0 = worst health state to 100 = best health state; scalp psoriasis: scalp affected = 1, not affected = 0; nail involvement: nails affected = 1, not affected = 0; inpatient treatment due to psoriasis at least once in the last 5 years: yes = 1, no = 0; relatives with psoriasis yes = 1, no = 0 b
B, regression coefficient; SE, standard error; OR, Odds Ratio (exponentiation of the B coefficient); CI, Confidence Interval
