Development and Validation of a Screening Questionnaire for Psoriatic Arthritis

Transcription

1 Development and Validation of a Screening Questionnaire for Psoriatic Arthritis Dafna D. Gladman 1, Catherine T. Schentag 1, Brian D. Tom 2, Vinod Chandran 1, Cheryl F. Rosen 1 Vernon T. Farewell 2 1 University of Toronto, Canada and 2 MRC Biostatistics Unit, Cambridge, UK Toronto Western Hospital

2 questionnaire (ToPAS) The CASPAR criteria for the classification of PsA should be helpful in diagnosing the disease High sensitivity and specificity in early PsA» Chandran V, et al. Arthritis Rheum 2006:54(S9):S717 High sensitivity and specificity in family medicine» Chandran V, et al Arthritis Rheum 2006:54: 4091 However, an assessment by a physician to document inflammatory arthritis is necessary

3 In certain clinical and epidemiological settings it is impossible to have all patients reviewed by a physician Therefore, a screening tool to identify patients who may have PsA is necessary

4 Objective To develop and validate a screening questionnaire to identify patients with a high likelihood of having PsA for use in clinical settings and epidemiological studies

5 Methods Development of ToPAS Review of symptoms and signs seen among patients with PsA Evaluation of the questionnaire by:» Patients with PsA» Patients attending a rheumatology clinic» Rheumatologists, dermatologists, epidemiologists, scientists

6 The Psoriatic Arthritis Clinic, Centre for Prognosis Studies in The Rheumataic Diseases Toronto Western Hospital, University Health Network, University of Toronto July 1999 Study # Toronto Psoriatic Arthritis Screening Questionnaire Date: / / yr mo da Please tick () each correct response or fill in the blank for all questions on both sides of the page Date of Birth : / / Gender o Male yr mo da o Female Ethnic Background: Figure 1 Skin rash on the elbows Figure 2 Pits in the nail Figure 3 Lifting of the nail 1a. Have you ever had a skin rash consisting of red AND silvery-white scaly areas particularly on the elbows, knees or scalp as shown in FIGURE 1? If YES b. At approximately what age did you first notice this skin rash? c. Do you have this rash now? 2. Have you ever noticed any of these changes in your fingernails a. Pits in the nails as shown in figure 2 b. Lifting of the nail from the nail bed as shown in figure 3? If YES a. At approximately what age did you first notice them? b. Do you have either of these nail changes now? 3. Have you ever seen a doctor about a skin rash? 4. Has a doctor ever diagnosed you with psoriasis? If YES a. At approximately what age did you first notice this skin rash? years old years old years old

7 5a. Have you ever had joint pain, joint stiffness or swollen red joints that was not the results of Injury? If YES a. At approximately what age did you first notice these symptoms? b. Do you have any symptoms now? 6. Have you ever had a sausage shaped swollen finger or toe that was not the result of an injury? 7. Have you ever had neck pain lasting at least 3 months that was not injury related? If YES a. Was the neck pain accompanied by stiffness? b. Do you have any neck pain now? 8. Have you ever had back pain lasting at least 3 months that was not injury related? If YES a. Was the back pain accompanied by stiffness? b. Do you have any back pain now? 9. Have you ever had a skin rash on any part of your body at the same time as joint pain, joint stiffness or swollen red joints? If YES a. At approximately what age did you first notice this skin rash? b. Do you have this rash now? 10. Have your ever seen a doctor about any joint pain? 11. Have you ever been diagnosed with any form of arthritis other than psoriatic arthritis? Rheumatoid arthritis Osteoarthritis Lupus (SLE) Fibromyalgia Ankylosing spondylitis Scleroderrma Other 12. Has a doctor ever diagnosed you with psoriatic arthritis? If Yes a. At what age were your first diagnosed? years old years old O O O O O O O years old

8 Testing ToPAS Methods ToPAS was administered to consecutive consenting patients attending 5 different clinics: 1. The University of Toronto PsA clinic 2. A psoriasis phototherapy centre 3. A general dermatology clinic 4. A general rheumatology clinic (excluding PsA patients) 5. A family medicine clinic

9 Confirming the diagnosis of PsA Patients who completed ToPAS were assessed by a rheumatologist» Standard protocol Methods» Complete history, physical examination, and where appropriate, radiographic assessment. Based on the protocol the rheumatologist diagnosed a patient with PsA if they had an inflammatory arthritis in the presence of psoriasis CASPAR criteria were applied

10 Methods: statistical analysis A three-step analysis strategy was adopted 1. A stepwise logistic regression to identify a model with the questions considered to be most important in discriminating between those who were diagnosed with PsA and those who were not 2. A logistic model was fitted to three clinically relevant domains for identifying PsA suggested from step 1: the skin, joints, and nails 3. A simple weighting of each of the domains used in step 2 was considered.» ROC curves obtained at each step

11 Results Group PsA clinic Psoriasis clinic Dermatology Rheumatology Family medicine Total PsA Dx (%) 134 (100) 39 (24.4) 2 ( 1.7) 0 ( 0) 3 ( 1.7)

12 Logistic regression model from backward stepwise selection Estimate Standard error P value Intercept Skin rash Pits Diagnosed Ps Joint pain Sausage digit Back pain Seen MD Other Dx O < < < Residual variance (df) AIC (469)

13 ROC Curve for initial logistic regression model Sensitivity Cut point 7.71 Sens: 94.2% Spec: 91.5% PV+: 81.6% PV-: 97.5% AUC: Specificity

14 Logistic regression model for the domain variables Variable Skin Domain Joint Domain Nail Domain Definition Skin rash + Seen doctor about skin rash + Psoriasis Dx (Count of yes answers: Range 0-3) Joint pain + Sausage digit + Seen doctor about joint pain (Count of yes answers: Range 0-3) Pits in nails or Lifting of nail (Yes or no: Yes =1, No = 0) Neck and back pain questions did not improve model (p = 0.46)

15 ROC Curve based on Domains Sensitivity Cut point 7.76 Sens: 90.3% Spec: 90.5% PV+: 78.9% PV-: 96.2% AUC: Specificity

16 Simplified weighting based on logistic regression Joints = 2, Skin = 1, Nail = 1 Discriminatory score: 2x (Joint domain variable) + 1x (Skin domain variable) + 1x (Nail domain variable)

17 ROC Curve based on Simplified Domains Sensitivity Cutpoint 8 Sens: 86.8% Spec: 93.1% PV+: 83.0% PV-: 94.8% AUC: Specificity

18 Sensitivity and specificity of ToPAS Patient groups* Psoriasis Dermatology Rheumatology Family medicine * Each grouped with PsA Sensitivity (95% CI) 89.1% (89.1, 93.2) 91.9% (85,7, 95.6) 92.6% (86.4, 96.1) 90.4% (83.9, 94.5) Specificity (95% CI) 86.3% (76.4, 92.5) 95.2% (88.0, 98.2) 85.7% (76.9, 91.5) 100%

19 Summary ToPAS was derived from features of PsA and input from patients and investigators ToPAS is simple, only 12 questions The simplified index derived ToPAS proved highly sensitive and specific in 4 groups of patients Psoriasis General dermatology General rheumatology Family medicine

20 Our simplified index derived from the ToPAS is very good at identifying those who are diagnosed with PsA and those who are not This instrument is now ready for further validation It should be tested in other centers to confirm its usefulness in screening for PsA It should be tested in family investigations

21 Acknowledgements Contribution of all the patients Support from: TAS CIHR ACE (UHN) CPSRD Toronto Western Hospital Krembil Foundation