The direct medical cost of rheumatoid arthritis in Hong Kong

Summary

Rheumatoid arthritis (RA) is an autoimmune disorder of unknown aetiology. Both treatment and rehabilitation for RA are costly. Knowledge of the cost of management of RA is important for better planning for allocation of medical resources, and the present study aimed to evaluate and describe the direct medical cost of the management of RA from the perspective of a public health organisation in Hong Kong.

A retrospective study was performed of RA patients at the Prince of Wales Hospital in Hong Kong. The study cohort consisted of randomly selected RA patients from the 1st January 2002 to the 31st December 2002. Cost items studied included hospital stay, outpatient clinic visits, diagnostic tests, medications, auxiliary care, and cost for management and prophylaxis of side effects induced by the drugs for RA management.

A total of 147 patients were included in the study. The average age and duration of disease of the subjects was 54.7 years (standard deviation 10.9 years) and 12.6 years (standard deviation 7.0 years), respectively. The annual direct medical cost per RA patient was HK$18,657 (US$1 = HK$7.8). Inpatient care contributed the highest proportion of the total cost (43.8%). The annual direct medical cost for the management of RA in Hong Kong was HK$443 million, which comprised 1.4% of the total healthcare budget in the year 2002.

The cost of RA has an economic impact on the healthcare budget in Hong Kong. Early and more aggressive measures could reduce the need for hospitalisation and hence reduce costs.

Keywords::

• rheumatoid arthritis
• direct medical cost
• inpatient cost
• Hong Kong

Introduction

Rheumatoid arthritis (RA) is an autoimmune disorder of unknown aetiology characterised by inflammatory arthritis of the synovial joints, usually in a symmetrical distribution. The usual clinical presentations of RA are painful and swollen joints with soft tissue inflammation, a decreased range of motion and morning stiffness. Joint erosion, deformities and loss of function may also occur. The disease affects a wide range of patients, including those in their 20s. The majority of RA patients are between 30 and 70 years of age. RA contributes to disabilities and has a high economic impact. An epidemiological study carried out in Hong Kong showed that arthritis represented the greatest chronic disease burden (30%) of the Hong Kong population aged >70 years old1. RA is the most common cause of disability among arthritic conditions.

As RA is a chronic and degenerative condition, it can be a very costly disease. The rapid increase in healthcare expenditure in all countries has led to an increased interest in the economic impact of individual diseases. Cost-of-illness (CoI) studies provide insight into the expenses associated with the prevention, detection and treatment of chronic diseases, including RA. The information from CoI studies provides a potentially useful decision-making aid for setting priorities in healthcare service delivery and research. However, limited information on the cost of managing RA is available in Hong Kong. The aim of the current study was to evaluate the direct medical cost of the management of RA and the extent of resource use in current practice from the perspective of a public health organisation in Hong Kong.

Methodology

This study was a retrospective evaluation of patients with a diagnosis of RA according to the criteria of the American College of Rheumatology (ACR) at the Princes of Wales Hospital (PWH) in Hong Kong. The PWH is a 1,200-bed acute general hospital serving low-to-middle income patients in the East New Territories region in Hong Kong. It is also a teaching hospital affiliated with The Chinese University of Hong Kong. The patient cohort included all RA patients who were followed-up at the PWH from the 1st January 2002 to the 31st December 2002. Medical charts of RA patients were selected and reviewed. Demographics, clinical characteristics, drug therapies, laboratory tests, diagnostic procedures, clinic visits, emergency department admissions and hospitalisations were identified and recorded during the medical chart review. Cost in this evaluation was defined as the sum of the cost of the items listed in Table 1. The unit costs of drugs and other resource items were based on the Hospital Authority drug acquisition cost 2003 and the Hong Kong Government Gazette 20032, respectively. Cost was presented in Hong Kong dollars (HK$7.8 = US$1). The direct medical cost was then projected and estimated for the total economic burden of RA in Hong Kong using the prevalence rate method. The total cost of RA management in Hong Kong was estimated by multiplying the cost calculated in this study by the total number of RA patients in Hong Kong using the prevalence rate. Costs were calculated from a public health organisation perspective in Hong Kong.

Table 1. Rheumatoid arthritis-related direct cost domains

Cost items
Inpatient management
Hospitalisation (days of hospital stay)
Procedures (surgeries, investigations)
Laboratory monitoring
Medications
Outpatient management
Clinic visits
Outpatient surgery
Diagnostic/therapeutic procedures and tests (e.g. radiography)
Emergency room visits
Medications (DMARDs, NSAIDs, steroids, analgesics, supplements)
Non-physician service utilisation (physiotherapist, occupational therapist, rehabilitation)
Cost for management/prophylaxis of side effects
Medications (gastroprotective drugs)
Investigations, monitoring (e.g. oesophagogastroduodenoscopy)
Clinic visits (e.g. eye clinic)

DMARDs, disease-modifying antirheumatic drugs; NSAIDs, non-steroidal anti-inflammatory drugs.

Normally distributed data were reported as the mean ± standard deviation (sd). Otherwise, data were reported as median values. Categorical variables were compared by χ2 statistics. Cost variables (medians) and other variables were compared using Mann–Whitney U-test (two sample groups) or Kruskal–Wallis test (three sample groups). Patients were stratified into different groups according to gender and the severity of disease. A p-value <0.05 was considered to be statistically significant (Microsoft Excel 2002 and SPSS 11.5.1 for Windows).

Results

The medical charts of 176 patients were reviewed. A total of 29 patients were excluded because they did not attend any outpatient clinics or receive any inpatient services during the study period. Disease severity was classified according to the ACR criteria. The demographic characteristics of the 147 patients are summarised in Table 2. Of the patients 18 (12.2%) required hospitalisation. Of these, 89% were female and 50% required surgical procedures during hospitalisation. The demographic characteristics of the 18 hospitalised patients are summarised in Table 3. These patients had a more severe classification of RA compared with non-hospitalised patients. The mean length of hospital stay was 9.8 ± 10.2 days. Female patients in the study cohort skewed the sample towards a younger age than in the random sample as a whole. They also had a longer history of the disease, but this was statistically insignificant. This observation was likely due to the small sample size. The cost summary of RA management is summarised in Table 4. The major cost driver was hospitalisation from the 18 patients, which accounted for 43.8% of total costs, followed by laboratory cost (19.2%) and outpatient care (15.4%). The drug cost contributed <10%, and 3% of the resources was spent on the management of side effects of the RA drug used. The reason for the high inpatient cost was due to the cost of surgical procedures, which accounted for 49% of the inpatient management cost. Of the total drug cost 80% was spent on disease-modifying antirheumatic drugs (DMARDs); and non-steroidal anti-inflammatory drugs (NSAIDs) such as naproxen accounted for 13% of the total drug cost. The DMARDs used in Hong Kong included methotrexate, hydroxychloroquine, azathioprine and gold compounds. In the current study, 81 patients (55.1%) received methotrexate (mean cost = HK$119.98), 58 patients (39.5%) used hydroxychloroquine (mean cost = HK$1,441.56), 50 patients (34.0%) used sulfasalazine (mean cost = HK$1,537.07), 9 patients (6.1%) used leflunomide (mean cost = HK$4,463.11), 4 patients (2.7%) used auranofin (mean cost = HK$2,803.50) and 2 patients (1.4%) used azathiopine (mean cost = HK$690.77).

Table 2. Demographic characteristics of the subjects*

Characteristic	Male	Female	All patients	p-value
Age (years)			54.7 ± 10.9
Gender, n (%)	34 (23.1)	113 (76.9)	147 (100)
Weight (kg)			54.5 ± 9.3
Duration of disease (years)			12.6 ± 7.0
No. of swollen joints			1.76 ± 2.04
No. of tender joints			1.42 ± 2.06
Early morning stiffness (min)			27.3 ± 62.7
ESR			36.2 ± 25.0
Age group (years), n(%)
<50	5 (14.7)	42 (37.2)	47 (32.0)	<0.01
50–60	17 (50.0)	42 (37.2)	59 (40.1)
>60	12 (35.3)	29 (25.7)	41 (27.9)
Disease severity, n (%)
Functional class I	18 (52.9)	44 (38.9)	62 (42.2)	>0.1
Functional class II	13 (38.2)	62 (54.9)	75 (51.0)
Functional class III	3 (8.8)	7 (6.2)	10 (6.8)
Duration of disease (years)	11.44 ± 6.24	12.95 ± 7.23

ESR, erythrocyte sedimentation rate (patients performed this test in the study period; n = 64).

*Data are mean ± standard deviation unless otherwise stated.

Table 3. Comparison of demographic data in patients with at least one hospital admission during the study period

	Hospitalisation, n (%)	Without hospitalisation, n (%)	All patients	p-value
No. of patients	18	129	147
Sex
Male	2 (11.1)	32 (24.8)	34 (23.1)	>0.1
Female	16 (88.9)	97 (75.2)	113 (76.9)
Age group (years)
<50	5 (27.8)	42 (32.6)	47 (32.0)	>0.1
50–60	9 (50.0)	50 (38.8)	59 (40.1)
>60	4 (22.2)	37 (28.7)	41 (27.9)
Disease severity
Functional class I	4 (22.2)	58 (45.0)	62 (42.2)	>0.1
Functional class II	11 (61.1)	64 (49.6)	75 (51.0)
Functional class III	3 (16.7)	7 (5.4)	10 (6.8)
Duration of disease (years) (mean ± sd)	13.5 ± 7.22	12.47 ± 6.96

sd, standard deviation.

Table 4. Direct medical cost of rheumatoid arthritis per patient per year

	Mean cost per patient year (HK$)	Median cost per patient per year (range) (HK$)	% of total
Inpatient cost	8,171.2	0 (0–209,921)	43.8
Outpatient cost	2,872.2	2,800 (700–10,900)	15.4
Laboratory cost	3,574.8	3,350 (0–8,510)	19.2
Radiography	1,368.6	0 (0–14,320)	7.3
Minor surgery	265.3	0 (0–7,500)	1.4
Drug cost	1,827.6	1,304 (0–12,879)	9.8
Management of side effects	577.6	66 (0–6,000)	3.1
Total	18,657.2	10,095 (1,400–21,715)	100.0
	Age group
	<50 years (n = 47)	50–60 years (n = 59)	>60 years (n = 41)
Average (± sd) cost of outpatient (HK$)	2,646 ± 1,199	3,061 ± 1,611	2,860 ± 1,060
Hospital stay in the past 12 months (HK$)
Average (± sd) cost of surgery	8,484 ± 30,941	1,233 ± 7,177	2,838 ± 10,559
Average (± sd) hospital cost	13,700 ± 47,007	3,978 ± 14,260	7,868 ± 29,929
Average (± sd) cost contributed to side-effect monitoring (HK$)
Laboratory cost	121 ± 289	227 ± 408	159 ± 420
OGD	128 ± 612	51 ± 391	0 ± 0
Liver biopsy	0 ± 0	102 ± 781	0 ± 0
Cost of eye clinic attendance	298 ± 579	190 ± 564	364 ± 613
Drug cost for management or prophylaxis of side effects	42 ± 8	26 ± 82	16 ± 30
Average total cost arising from side effect of medications	588 ± 859	596 ± 1,049	589 ± 678
Average (± sd) drug cost for disease management (HK$) [%]
NSAIDs	190 ± 326 [11.9]	306 ± 497 [14.5]	176 ± 271 [10.3]
DMARDs	1,285 ± 1,691 [80.8]	1,564 ± 2,219 [74.3]	1,455 ± 1,713 [85.2]
Glucocorticoids	33 ± 85 [2.1]	19 ± 41 [0.9]	15 ± 27 [0.9]
Analgesics	9 ± 29 [0.6]	20 ± 33 [1.0]	29 ± 35 [1.7]
Others	72 ± 140 [4.5]	196 ± 1,028 [9.3]	31 ± 64 [1.8]
Total drug cost	1,590 ± 1,798	2,105 ± 2,460	1,707 ± 1,724
Total (± sd) cost of laboratory monitoring (HK$)	3,676 ± 1,739.59	3,597 ± 1,728.88	3,427 ± 1,743.46
Total (± sd) cost of radiological procedure (HK$)	1,158 ± 2,090.44	1,769 ± 2,640.3	1,034 ± 1,712.7

sd, standard deviation; HK$, Hong Kong dollar; OGD, oesophagogastroduodenoscopy; NSAIDs, non-steroidal anti-inflammatory drugs; DMARDs, disease-modifying antirheumatic drugs.

Based on local epidemiological data, the prevalence rate of RA in Hong Kong is 0.35%. Extrapolation from this study suggests the total cost of RA management in Hong Kong to be approximately HK$443 million per year, or 1.4% of the local overall healthcare expenditures for the year 2001–2002.

Discussion

RA is a debilitating, degenerative illness with significant economic consequences for patients as well as the healthcare system. It has been shown that individuals with RA have 3 times the direct medical costs, 2 times the hospitalisation rate and 10 times the work disability rate of an age- and sex-matched population3. However, limited studies regarding the economic evaluation of RA are reported in Southern China.

The current study estimated the total direct medical cost in 2002 for the management of a RA patient to be HK$18,657 (US$2,392), which is comparatively lower than other foreign countries such the US4 (US$9,519), UK5 (US$5,771) and Germany (US$2,975)6. The different healthcare systems and insurance reimbursement systems may explain the reason for these differences. Similar differences were noted in the author's previous study on the cost of acute myocardial infarction7. In Hong Kong, the government covers or subsidises the majority (>95%) of the healthcare cost, and healthcare expenditures only account for approximately 5% of the gross domestic product8. This is much less than other Western countries such as the US, UK, Canada and Australia, which ranged from 8 to 13%8. As a result, the healthcare resources in Hong Kong are more controlled than in other Western countries.

In the current study, the inpatient cost from the 18 hospitalised patients accounted for >40% of the direct medical cost owing to surgical operations of total knee and hip replacement, which required longer hospital stay. It is noteworthy that a difference was observed in the US and Germany. In the US, only 17% of the total was attributable to hospitalisation cost, whilst most of the cost was made up of the drug cost5. In Germany, outpatient cost was the dominant cost driver, which made up 74% of the total cost, and inpatient cost was approximately 24%6.

Drug cost in the current study only accounted for approximately 10% of the total direct medical cost. In the UK, a systematic review has been performed to estimate the economic burden of RA4. It showed that the medication cost constituted between 8 and 24% of the total medical cost4. In the US, the drug cost accounted for up to 66% of the total direct medical cost5. The discrepancy could be explained by differences in prescribing patterns of medications. The reason for lower drug cost in RA patients in Hong Kong is due to lower utilisation of DMARDs and newer biological agents in RA management. Newer biological agents such as infliximab and etanercept have been used in other countries. Studies demonstrated the efficacy of etanercept and infliximab in improving clinical signs and symptoms as well as improving quality of life in RA patients9–11. In the UK, infliximab was also deemed to be cost effective for the treatment of RA11. Furthermore, the newer agents required less routine laboratory monitoring for the prevention of adverse events. However, older NSAIDs and DMARDs are usually prescribed to RA patients in Hong Kong. A local study has revealed that the most common and potentially serious adverse effect of NSAIDs is gastrointestinal mucosal injury12, which could increase the risk of peptic ulcer disease by 4–6-fold13. Hence, prophylactic treatment is necessary for those patients undergoing NSAID therapy. Patients may require routine oesophagogastroduodenoscopy. As a result, the use of a cyclooxygenase-2 inhibitor, such as celecoxib, may have a role in reducing the cost of the disease because it has fewer gastrointestinal side effects compared with traditional therapy using NSAIDs. Similarly, ocular damage is caused by the toxicity of hydroxychloroquine (HCQ), which is one of the most commonly used DMARDs in RA management. Patients who take HCQ are required to visit an eye clinic routinely for eye examination. These older agents require routine laboratory monitoring, which also leads to increased direct medical cost. As mentioned previously, routine laboratory cost ranked second in the total direct medical cost. As a result, reducing medication cost by using older agents does not necessary result in cost saving.

In order to save cost, it is important to look at the major cost driver, which is inpatient cost. Most patients require inpatient care mainly due to worsening of the RA condition leading to surgical intervention such as total hip or knee replacement. In the current study, the largest portion of the inpatient cost of management of RA was shared by only 18 patients. In other words, preventing patients from hospitalisation by slowing the progression of the disease could decrease the economic burden. Based on this concept, some countries such as the UK have changed their clinical management of RA by prescribing more aggressive treatment earlier in the disease process14. A pharmacoeconomic review further suggested that the use of more effective treatment, such as infliximab, could delay radiographic progression and the need for surgery and, therefore, may result in lower hospitalisation cost10. Verstappen et al15 stated that ‘Functional disability was associated with high costs and was a predictor of high costs. Thus, a rapid improvement of functional disability might reduce the financial burden on individual RA patients, health services, and the society. The concept of early aggressive treatment of RA is supported by these CoI data’.

In the current study, the highest total cost was required for the management of RA in the youngest group (<50 years old). This group of patients had the longest average duration of hospital stay (14.4 days) and the highest cost for surgical procedures and inpatient hospitalisation. The inpatient costs constituted more than one-half of the total cost of RA management in this group of patients, facing the fact that younger patients have disease progression to the stage that requires joint replacement or implant. In contrast, the age groups 50–60 years and >60 years had the lowest cost, especially in the inpatient section, which might be due either to a stable disease condition or less favourable selection for surgical procedures after balancing the risk and benefit. It is an inevitable fact that the trend of aging in the Hong Kong population would increase the burden to the healthcare system. The prevalence of RA is expected to be higher in the future. Reallocation of resources should be considered for earlier and more effective drug therapy in order to reduce overall economic costs. More pharmacoeconomic studies would provide current guidance for decision making.

The current CoI study has its limitations. The number sampled may be sufficient to provide an overall representation, however, the relatively small cohort may not be able to detect the association of the demographic data and clinical variables with the high-cost groups. Furthermore, as the study was a retrospective medical chart review, it could only estimate direct medical cost but not the indirect costs and other related out-of-pocket costs including sick leave, job interference, alternative medicines and transportation costs. The impact of these indirect costs, together with the social impact and quality of life for the RA patients in Hong Kong remain unclear and more studies should be carried out in this field. An Australian study16 showed that people with RA reported worse health status than their age-related peers as measured by the Health Status Questionnaire Short Form-36 and the disease-specific index Health Assessment Questionnaire. Thus, a step further is to estimate the indirect medical cost of RA. This would give a more complete picture of how much has been spent in the management of RA. In addition, there may be possible bias in using one hospital in Hong Kong to project for the total economic burden of RA in Hong Kong. However, in the Hong Kong healthcare system, over 95% of citizens utilised the health services provided by the government. As a result, the majority of RA patients are seen in public hospitals and clinics. PWH is one of the seven regional hospitals in Hong Kong. Therefore, the care and practice for RA patients at the PWH reflected the whole situation of RA patients in Hong Kong.

Despite the limitations, cost estimates for chronic diseases are of paramount importance in health economic analyses of the rising burden of chronic disease and disability in societies. This is particularly true when there is unlimited demand with limited resources. CoI studies have been carried out for many chronic diseases worldwide. All studies showed considerable economic burden to society whether in terms of direct or indirect costs17. The availability of such data assists policy makers in formulating health policies to minimise costs and facilitates decisions regarding the choice of drug treatments or methods of service delivery.

Conclusion

The study demonstrated that RA poses a significant economic burden to the healthcare budget in Hong Kong. Hospitalisation cost shared the greatest proportion of the direct medical cost, whilst drug cost constituted only a small portion of the entire cost of management. More research is necessary to determine the full economic impact and indirect costs of RA and to examine the cost effectiveness of different treatment alternatives in order to provide a better picture of the management of RA in Hong Kong.