Chronic diseases

Osteoarthritis hip and knee (algorithm)


Data files
LASAzoa1: LASA-B, LASA-C, LASA-D, LASA-E, LASA-F first cohort, pdf in preparation)
LASAzoa2: temporarily not available

Contact: Marjolein Visser (m.visser@vumc.nl)

Background
Osteoarthritis (OA) is a highly prevalent chronic rheumatic disorder in western populations and is a leading cause of pain and disability among elderly [1]. It is expected that the prevalence of OA will increase with 38% between 2000 and 2020 in the Netherlands [2]. Although much research is conducted on OA, there is no consensus on how to assess the presence of OA. Therefore, an algorithm to assess osteoarthritis of the hip and knee was developed in LASA.
Note: in a later side study in which LASA participated, i.e.
The European Project on OsteoArthritis (EPOSA), clinical osteoarthritis was defined according to the criteria of the American College of Rheumatology [3].

OA algorithm
With literature and the available LASA data, an algorithm for the presence of OA was made in 2007. The LASA study contains self-reported data, general practitioner (GP) data and x-ray data of the spinal cord (T4-L5) and the hip (at C and D cycles) on OA. As the correlation between radiographic evidence and symptomatic OA is rather weak [4], symptomatic OA was defined by means of self-reported data and GP data only. The focus was on knee and hip OA, as they are the most prevalent locations of OA: according to the Dutch GP registration 2000 approximately 77% of all OA locations are of the knee and hip [5]. Medication use was not taken into account as there is no arthritis specific medication. Pain was debated, but after considerations from Prof. J. Dekker (Professor of Allied Health Care at the Department of Psychiatry and the Department of Rehabilitation Medicine, VUmc), it was not included in the algorithm. Many OA patients have pain, however, there are no valid criteria for epidemiological use that tell us which people with joint pain have osteoarthritis [6]. Furthermore, joint pain is a follow-up question in LASA, so only respondents with self-reported OA provide an answer.
Previously in LASA, osteoarthritis and rheumatoid arthritis were categorised as one variable [7]. In this decision tree we separated OA and RA, as it is presumed respondents can differentiate between the two diseases as they are explained by the interviewer. However, it remains possible some misclassification is present.
The algorithm is based on data from the first LASA cohort to assess prevalent and incident OA (cycles B–F).

Data sources
Data files and variables used in the OA algorithm:

Cross-sectional decisions
Question xrheum01 stated ‘Do you have osteoarthritis in your knees, hips or hands?’ At B the response categories were; Missing, No and Yes. At the C, D, E and F cycles the response categories yes and no were extended to: ‘No, never’; ‘No, (previous) rheum01 Yes’; ‘Yes, (previous) rheum01 No’; ‘Yes, (previous) rheum01 Yes’. For each cycle, the two response categories starting with ‘No,..’ were categorized as No, and the two categories starting with ‘Yes,..’ were categorized as Yes.

The final cross-sectional OA categories created are Missing, No, Possible and Yes, as is illustrated by the decision tree. The decision tree is explained as:

In comparing the presence of OA in the main interview with GP reported OA, some considerations had to be made. First, in this algorithm the opinion of the respondent weighs heavier than that of the GP as we were interested in self-reported symptomatic OA and because many cases of osteoarthritis are not known to the GP [7]. Second, as the GP data collection in 2000/01 (CG01) is used for the C and D cross-sectional decisions, subjects at C could be misclassified, because the GP data was collected after the D cycle. For example, respondents who answered to have no OA at the C measurement and the GP answer was yes could be classified as possible, while the GP answer was assessed after the D measurement. However, the GP questionnaire contains the branching question ‘when was the OA diagnosed?’ when presence of OA is marked. In the case that this date was after the C-cycle or this date was missing, respondents’ answers were changed into no OA. Finally, additional data from telephone interviews were not used because only the presence of the main chronic diseases are asked. Without additional branching questions there is no information on the location of OA so hip or knee OA cannot be selected.

Questionnaires
PM

Variable information
PM

Availability of information per wave1, 2

Knee

N=3107

N=3107

N=3107

N=3107

N=1002

N=4109

N=4109

B

C

D

E


2B*

F

G

Definite

183

190

157

126

35

150

153

Possible

529

481

346

321

192

432

349

No

2323

1621

1180

917

771

1230

995

Missing

72

253

393

327

4

353

321

Dropout (cum)

0

562

1031

1416

0

1944

2291

Hip

N=3107

N=3107

N=3107

N=3107

N=1002

N=4109

N=4109

B

C

D

E


2B*

F

G

Definite

150

148

118

81

26

112

97

Possible

433

385

257

246

146

314

263

No

2452

1759

1308

1037

826

1382

1135

Missing

72

253

393

327

4

357

323

Dropout (cum)

0

562

1031

1416

0

1944

2291

1 More information about the LASA data collection waves is available here.

2 These numbers are cross-sectional, and thus not longitudinally cleaned.

*  2B=baseline second cohort

Use of algorithm
The syntax of the OA algorithm can be found here. This algorithm was created for defining knee and hip OA for a project on physical activity and the onset of OA. Some suggestions for longitudinal cleaning and reducing the number of missings are added to the syntax.

Previous use in LASA
Verweij, L.M., Van Schoor , N.M., Deeg, D.J.H., Dekker, J., Visser, M. (2009). Physical activity and incident clinical knee osteoarthritis in older adults. Arthritis & Rheumatism (Arthritis Care & Research), 61, 2, 152-157.

References

  1. Bone and Joint Decade. European Action Towards Better Musculoskeletal Health. 2-6-2005.
  2. Schouten JSAG, Poos MJJC, Gijsen R. Neemt het aantal mensen met artrose toe of af? In: Volksgezondheid Toekomst Verkenning (RIVM) 15-11-2002.
  3. Altman RD. Classification of disease; osteoarthritis. Semin Arthritis Rheum. 1991; 20 (suppl. 2):40-47.
  4. Dieppe PA, Lohmander LS. Pathogenesis and management of pain in osteoarthritis. Lancet. 2005; 365 (9463): 965-73.
  5. Gijsen R (RIVM), Poos MJJC (RIVM). Achtergronden en details bij cijfers uit huisartsenregistraties. In: Volksgezondheid Toekomst Verkenning, Nationaal Kompas Volksgezondheid. Bilthoven: RIVM, 16 mei 2003.
  6. Felson DT. Osteoarthritis of the knee. New England Journal of Medicine. 2006; 354: 841-8.
  7. Kriegsman DMW, Penninx BWJH, Eijk JThM van, Boeke AJP, Deeg DJH (1996). Self reports and general practitioner information on the presence of chronic diseases in community dwelling elderly. A study on the accuracy of patients' self-reports and on determinants of inaccuracy. J Clin Epidemiol, 49:1407-17.