Chapter 6
Methodological Appendix 

Table 6A-1    Arthritis and related diagnoses
ICD-9 Diagnosis Code
274	Gout
446	Polyarteritis nodosa and allied health conditions
710	Diffuse diseases of connective tissue
711	Arthroplasty associated with infections
713	Arthropathies associated with other disorders classified elsewhere
714	Rheumatoid arthritis and other inflammatory polyarthropathies
715	Osteoarthrosis and allied disorders
716	Other and unspecified arthropathies
717	Internal derangement of the knee
718	Other derangement of joint
719	Other and unspecified disorders of the joint
720	Ankylosing spondylitis and other inflammatory spondylopathies
725	Polymyalgia rheumatica
726	Peripheral enthesopathies and allied syndromes
727	Other disorders of synovium, tendon and bursa
728	Disorders of muscle, ligament and fascia
729	Other disorders of soft tissues
739	Other diseases of the MSK system and connective tissue

Table 6A-2    Arthritis relevant orthopedic surgical procedure CCP codes
CCP Code	Procedure	CCP Code	Procedure
Joint Replacement (Primary and Revision)
Hip Replacements
9359	Total hip replacement	9353	Revision of hip replacement
9351	Total hip replacement w. methyl methacrylate	9359	Revision of hip replacement
9352	Revision of hip replacement
Knee Replacements
9340	Revision of total knee replacement	9341	Total knee replacement
Other Joint Replacements
9348	Total ankle replacement	9387	Arthroplasty of carpals without synthetic prosthesis
9331	Arthoplasty of foot & toe w. synthetic prosthesis	9381	Total shoulder replacement
9339	Other arthroplasty of foot and toe	9384	Arthroplasty of elbow with synthetic prosthesis
9371	Arthroplasty of hand/finger w. synthetic prosthesis	9385	Other repair of elbow
9386	Arthroplasty of carpals with synthetic prosthesis
Knee ProceduresI
9245	Synovectomy	9322	Arthrodesis of knee
9285	Arthroscopy	9205	Arthrotomy for removal of prosthesis
8925	Wedge osteotomy	9215	Other arthrotomy
9225	Division of joint capsule, ligament, or cartilage	9232	Excision of semilunar cartilage of knee
9265	Other excision of joint
Spine Procedures
9301	Atlas-axis spinal fusion	9307	Lumbosacral spinal fusion
9302	Other cervical spinal fusion	9308	Refusion of spine
9305	Other dorsolumbar spine fusion	9309	Other spine fusion
Other Joint ProceduresII
8920	Wedge osteotomy - scap/clav/thor	9204	Arthrotomy/removal of prosthetic hip
8921	Wedge osteotomy - humerus	9206	Fusion/arthrodesis - interphalangeal fusion
8922	Wedge osteotomy - radius and ulna	9214	Other arthrotomy - hip
8923	Wedge osteotomy - carpal/metacarp	9224	Division of joint various - hip
8926	Wedge osteotomy - tibia/fibula	9240	Synovectomy of shoulder
8927	Wedge osteotomy - tarsus/metatarsus	9241	Synovectomy of elbow
8928	Wedge osteotomy - tarsus/metatarsus	9242	Synovectomy of wrist
8929	Wedge osteotomy of unspecific site	9243	Synovectomy of hand/finger
9200	Arthrotomy for removal of prosthesis in shoulder	9244	Synovectomy of hip
9201	Arthrotomy for removal of prosthesis elbow	9246	Synovectomy of ankle
9202	Arthrotomy for removal of prosthesis wrist	9247	Synovectomy of foot/toe
9203	Arthrotomy for removal of prosthesis hand/finger	9248	Synovectomy of other site
9207	Arthrotomy for removal of prosthesis of foot/toe	9249	Synovectomy of unspecific site
9208	Arthrotomy - prosthesis removal, site non-specific	9264	Other excision - hip
9209	Arthrotomy - prosthesis removal, site non-specific	9280	Arthroscopy of shoulder
9210	Other arthrotomy - shoulder	9281	Arthroscopy of elbow
9211	Other arthrotomy - elbow	9282	Arthroscopy of wrist
9212	Other arthrotomy - wrist	9283	Arthroscopy of hand/finger
9213	Other arthrotomy - wrist	9284	Arthroscopy - hip
9216	Other arthrotomy - ankle	9286	Arthroscopy of ankle
9217	Other arthrotomy - foot/toe	9287	Arthroscopy of foot/toe
9218	Other arthrotomy - other spec site	9288	Arthroscopy of other specific site
9219	Other arthrotomy in an unspecific site	9289	Arthroscopy of unspecific site
9220	Division of joint various - shoulder	9311	Ankle fusion
9221	Division of joint various - elbow	9312	Fusion/arthrodesis - triple
9222	Division of joint various - wrist	9313	Fusion/arthrodesis - subtalar fusion
9223	Division of joint various - hand/finger	9314	Fusion/arthrodesis - midtarsal fusion
9226	Division of joint various - ankle	9315	Fusion/arthrodesis - tarsometatarsal fusion
9227	Division of joint various - foot/toe	9316	Fusion/arthrodesis - metatarsophalangeal fusion
9228	Division of joint various - other specific site	9317	Fusion/arthrodesis - other fusion of the foot
9229	Division of joint various - unspecific joint	9318	Fusion/arthrodesis - other fusion of the toe
9260	Other excision - shoulder	9321	Arthrodesis - hip
9261	Other excision - elbow	9323	Fusion/arthrodesis - shoulder
9262	Other excision - wrist	9324	Fusion/arthrodesis - elbow
9263	Other excision - hand/finger	9325	Fusion/arthrodesis - carporadial fusion
9266	Other excision - ankle	9326	Fusion/arthrodesis - metacarpal fusion
9267	Other excision - foot/toe	9327	Fusion/arthrodesis - metacarpophalangeal fusion
9268	Other excision - other specific site	9328	Fusion/arthrodesis - interphalageal fusion
9269	Other excision - unspecific joint	9329	Fusion/arthrodesis - unspecified joints
9392	Injection - substance into joint or ligament
8924	Wedge osteotomy - femur
I    Excludes if coded with hip or knee replacement codes  II    Excludes if coded with any knee procedure codes or any hip replacement codes

Data Quality Issues 

Systematic differences in coding practices among provinces may limit the interpretation of provincial variations in hospital admissions and surgical procedures for arthritis and related conditions. Detailed coding of diagnosis by some provinces would overestimate the rate of arthritis and related admissions/surgeries in comparison to provinces that systematically record fewer diagnoses. Systematic variation in coding practices by province may also be the result of provincial differences in remuneration practices (such as the use of complexity scores for reimbursement purposes). In addition, coding practices may change over time. For example, as the non-articular manifestations of arthritis or its treatment are increasingly recognized, arthritis is more likely to be coded as a contributing diagnosis for medical admissions. The abstracting system (system of recording data from hospitals) in Manitoba and Quebec differs from that of other provinces. As a result, moderate interprovincial comparisons involving these two provinces must be interpreted with caution. 

Provincial differences involving infrequently performed procedures in the smaller provinces should also be interpreted with caution, since small coding errors or minor changes in practices could result in large differences in rates. Trends in surgical procedures draw only on available data from Ontario, British Columbia and New Brunswick and may not, therefore, reflect all of Canada. 

Technical Methods 

Data Sources: Information was extracted from both the CIHI* Discharge Abstract Database (DAD) and Hospital Morbidity Database (HMDB), and the Canadian Joint Replacement Registry. 

Arthritis and Related Orthopedic Surgical Procedures: A list of approximately 130 ICD-9-CM arthritis-related orthopedic procedures was devised in consultation with a practising orthopedic surgeon (NNM). These procedures were categorized into three groups based on the frequency of the procedure and the joint involved (see Table 6A-1). 

Arthritis and Related Diagnosis: Only individuals with an ICD-9 based diagnosis for arthritis or a related condition (see Table 6A-2) in any one of the available diagnosis fields were included in the analysis. 

Surgical Procedures: The patient's sex, year of birth, province of residence, discharge date, ICD-9 based diagnoses, up to 10 surgical procedure codes (CCP) and patient facility (inpatient or outpatient) were extracted from DAD for fiscal years 1994/95 to 2000/01 for episodes that involved at least one arthritis-related orthopedic surgical procedure. 

Hospital Admissions: The patient's sex, year of birth, province of residence, discharge date, ICD-based diagnoses and surgical procedure flag [ccp-proc-code1-12] were extracted from HMDB for fiscal years 1994/95 to 2000/01. All admissions for obstetric deliveries were excluded (using the ICD-9 diagnostic codes 650,651,652,653,654,655, 656,657,658,659 in any of the 16 diagnosis fields). 

Exclusions: All analysis in this chapter excluded the following: non-acute care cases, individuals under the age of 15 years (except for total hip and knee replacement data, which included all ages), entries with serious coding errors, newborn cases, cases with invalid health card numbers and admissions to international institutions. For data by province, age or sex, cases with no known province of residence, age or sex respectively were excluded. For surgical procedures other than hip and knee replacement, cases were excluded if the procedure was cancelled, or if it was coded as occurring before admission or in another hospital. 

Analysis: Data from both DAD and HMDB were stratified by province, fiscal year, age (groups: 15-44 [< 45 for hip and knee replacements], 45-54, 55-64, 64-74, and 75+ years) and sex. Surgical procedures were further stratified by procedure group. Geographical location was determined using patient residence, except for length-of-stay data that used the location where the procedure took place. 

Coefficient of variation, used to quantify variation in surgery rates among provinces, is the ratio of the standard deviation of the rates of procedures across the provinces to the mean rate - i.e., the rate for Canada. 

Since only Ontario, New Brunswick and British Columbia have consistently submitted data to DAD since 1994, time trends in the number and rate of orthopedic procedures draw on data from only these three provinces. By 2000, data were available for all of Canada excluding Manitoba, Alberta and Quebec. Canadian totals for the year 2000 include data from the available regions. 

References 

1.    Girard F, Guillemin F, Novella JL, Valckenaere I, Krzanowska K, Vitry F, et al. Health-care use by rheumatoid arthritis patients compared with non-arthritic subjects. Rheumatology 2002;41:167-75. 

2.    Gabriel SE, Crowson CS, Campion ME, O'Fallon WM. Direct medical costs unique to people with arthritis. J Rheumatol 1997;24:719-25. 

3.    Gabriel SE, Crowson CS, Campion ME, O'Fallon WM. Indirect and nonmedical costs among people with rheumatoid arthritis and osteoarthritis compared with nonarthritic controls. J Rheumatol 1997;24:43-8. 

4.    Anderson RB, Needleman RD, Gatter RA, Andrews RP, Scarola JA. Patient outcome following inpatient vs outpatient treatment of rheumatoid arthritis. J Rheumatol 1988;15:556-60. 

5.    Hunt SA, Jazrawi LM, Sherman OH. Arthroscopic management of osteoarthritis of the knee. J Am Acad Orthop Surg 2002;10:356-63. 

6.    Ostendorf M, Johnell O, Malchau H, Dhert WJ, Schrijvers AJ, Verbout AJ. The epidemiology of total hip replacement in The Netherlands and Sweden: present status and future needs. Acta Orthop Scand 2002;73:282-6. 

7.    Esmail N, Walker M. Waiting Your Turn: Hospital Waiting Lists in Canada, 12th edition. Vancouver: Fraser Institute, 2002. 

8.    Hawker GA, Wright JG, Coyte PC, Williams JI, Harvey B, Glazier R, et al. Differences between men and women in the rate of use of hip and knee arthroplasty. N Engl J Med 2000;342:1016-22. 

9.    Moseley JB, O'Malley K, Petersen NJ, Menke TJ, Brody BA, Kuykendall DH, et al. A controlled trial of arthroscopic surgery for osteoarthritis of the knee. N Engl J Med 2002;347:81-8. 

10.    Kalunian KC, Moreland LW, Klashman DJ, Brion PH, Concoff AL, Myers S, et al. Visually-guided irrigation in patients with early knee osteoarthritis: a multicenter randomized, controlled trial 1. Osteoarthritis Cartilage 2000;8:412-8. 

11.    Bradley JD, Heilman DK, Katz BP, Gsell P, Wallick JE, Brandt KD. Tidal irrigation as treatment for knee osteoarthritis: a sham-controlled, randomized, double-blinded evaluation. Arthritis Rheum 2002;46:100-8. 

12.    Coyte PC, Hawker G, Wright JG. Variations in knee replacement utilization rates and the supply of health professionals in Ontario, Canada. J Rheumatol 1996;23:1214-20. 

13.    Naylor CD. Variations in surgical services over time and by site of residence. In: Naylor CD, Anderson GM, Goel V, editors. Patterns of health care in Ontario. Toronto: Institute for Clinical Evaluative Sciences, 1994;69-124. 

14.    Wright JG, Hawker GA, Bombardier C, Croxford R, Dittus RS, Freund DA, et al. Physician enthusiasm as an explanation for area variation in the utilization of knee replacement surgery. Med Care 1999;37:946-56. 

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*    Parts of this material are based on data and information provided by CIHI. However, the analyses, conclusions, opinions and statements expressed herein are those of the authors and not necessarily of CIHI. 

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