Development and Validation of a Screening Questionnaire for Psoriatic Arthritis

(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}

(2)

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

Toronto Psoriatic Arthritis Screening

questionnaire (ToPAS)

(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

Toronto Psoriatic Arthritis Screening

Questionnaire (ToPAS)

(4)

Toronto Psoriatic Arthritis Screening

Questionnaire (ToPAS)

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

Toronto Psoriatic Arthritis Screening

Questionnaire (ToPAS)

(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 Ethnic Background:

yr mo da o Female

Figure 1

Skin rash on the elbows Figure 2Pits in the nail

Figure 3

Lifting of the nail

O Yes O No ______ years old

4. Has a doctor ever diagnosed you with psoriasis?

If YES a. At approximately what age did you first notice this skin rash?

O Yes O No

3. Have you ever seen a doctor about a skin rash?

O Yes O No O Yes O No ______ years old O Yes O No

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?

O Yes O No ______ years old O Yes O No

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?

(7)

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?

O Yes O No O Yes O No O Yes O No

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?

O Yes O No O O O O O O O

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 O Yes O No ______ years old

12. Has a doctor ever diagnosed you with psoriatic arthritis?

If Yes a. At what age were your first diagnosed?

O Yes O No

10. Have your ever seen a doctor about any joint pain?

O Yes O No O Yes O No O Yes O No

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?

O Yes O No

6. Have you ever had a “sausage shaped” swollen finger or toe that was not the result of an injury?

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?

(8)

Testing ToPAS

• 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

Toronto Psoriatic Arthritis Screening

Questionnaire (ToPAS)

(9)

Confirming the diagnosis of PsA

• Patients who completed ToPAS were

assessed by a rheumatologist

»

Standard protocol

»

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

Toronto Psoriatic Arthritis Screening

Questionnaire (ToPAS)

(10)

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

Toronto Psoriatic Arthritis Screening

Questionnaire (ToPAS)

(11)

Toronto Psoriatic Arthritis Screening

Questionnaire (ToPAS)

178

135

118

123

134 Total

3 ( 1.7)

Family medicine

0 ( 0)

Rheumatology

2 ( 1.7)

Dermatology

39 (24.4)

Psoriasis clinic

134 (100)

PsA clinic

PsA Dx (%)

Group

Results

(12)

572.73 (469)

192.62 Residual variance (df)

AIC

<0.0001

0.060

0.051 <0.0001

0.001 <0.0001

0.060

0.001

0.002

1.08

0.54

0.43

0.54

0.94

0.40

0.41

0.70

0.43 -8.56

1.02

0.84

2.53

3.05

1.89

0.77

2.34 -1.36

Intercept

Skin rash

Pits

Diagnosed Ps

Joint pain

Sausage digit

Back pain

Seen MD

Other Dx

P value

Standard

error

Estimate

O

Toronto Psoriatic Arthritis Screening

Questionnaire (ToPAS)

(13)

0.0 0.2 0.4 0.6 0.8 1.0 0. 0 0. 2 0. 4 0. 6 0. 8 1. 0 1-Specificity S en si ti vi ty

Cut point 7.71

Sens: 94.2%

Spec: 91.5%

PV+: 81.6%

PV-: 97.5%

ROC Curve for initial logistic regression model

(14)

Pits in nails or Lifting of nail

(Yes or no: Yes =1, No = 0)

Nail Domain

Neck and back pain questions did not improve model (p = 0.46)

Joint pain + Sausage digit + Seen doctor

about joint pain

(Count of ‘yes’ answers: Range 0-3)

Joint Domain

Skin rash + Seen doctor about skin rash

+ Psoriasis Dx

(Count of ‘yes’ answers: Range 0-3)

Skin Domain

Definition

Variable

Toronto Psoriatic Arthritis Screening

Questionnaire (ToPAS)

(15)

0.0 0.2 0.4 0.6 0.8 1.0 0. 0 0. 2 0. 4 0. 6 0. 8 1. 0 1-Specificity S en si tiv ity

Cut point 7.76

Sens: 90.3%

Spec: 90.5%

PV+: 78.9%

PV-: 96.2%

ROC Curve based on Domains

(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)

Toronto Psoriatic Arthritis Screening

Questionnaire (ToPAS)

(17)

0.0 0.2 0.4 0.6 0.8 1.0 0. 0 0. 2 0. 4 0. 6 0. 8 1. 0 1-Specificity S en si tiv ity