Not all "quality-adjusted life years" are equal.

BACKGROUND: There is evidence that utility elicitation methods used in the calculation of quality-adjusted life years (QALYs) yield different results. It is not clear how these differences impact economic evaluations. METHODS: Using a mathematical model incorporating data on efficacy, costs, and utility values, we simulated the experiences of 100,000 hypothetical rheumatoid arthritis patients over 10 years (50,000 exposed to infliximab plus methotrexate [MTX] and 50,000 exposed to MTX alone). QALYs, were derived from the Health Utilities Index 2 and 3 (HUI2 and HUI3), the Short Form 6-D (SF-6D), and the Euroqol 5-D (EQ-5D). Incremental cost-utility ratios were determined using each instrument to calculate QALYs and the results were compared using cost-effectiveness acceptability curves. RESULTS: Using the different utility measurement methods, the mean difference in QALYs between the infliximab plus MTX and MTX groups ranged from a high of 1.95 QALYs (95% CI=1.93-1.97) using the HUI3 to 0.89 QALYs (95% CI=0.88-0.91) using the SF-6D. Adopting the commonly cited value of society's willingness to pay for a QALY of $50,000, 91% of the simulations favored the cost utility of infliximab plus MTX when using the HUI3 to calculate QALYs. However, when using the EQ-5D, HUI2, or the SF-6D utility values to calculate QALYS, the proportion of simulations that favored the cost utility of infliximab were 63%, 45%, and 12%, respectively. CONCLUSION: Depending on the method for determining utility values used in the calculation of QALYs, very different incremental cost-utility ratios are generated.

The impact of low family income on self-reported health outcomes in patients with rheumatoid arthritis within a publicly funded health-care environment.

OBJECTIVE: Self-rated health (SRH) is an independent, strong predictor of morbidity and mortality. Socio-economic status (SES) is strongly associated with SRH. This study investigated the relationship between SES and SRH outcomes in a sample of patients with rheumatoid arthritis (RA) in Canada. METHODS: Both generic preference-based [Health Utilities Index Mark 3 (HUI3) and Short Form 6D (SF-6D)] and non-preference-based [disease-specific (Rheumatoid Arthritis Quality of Life, RAQoL) and a functional status (Health Assessment Questionnaire, HAQ)] SRH questionnaires were administered to 313 RA patients. Both proximate (education and annual household income) and contextual (neighbourhood income, education and unemployment) measures of SES were captured. Ordinary least squares (OLS) regression was used to adjust for RA severity while assessing the relationship between SRH and SES measures. Two-stage least-squares (TSLS) regression was used to determine if there was an inter-relationship between SES and SRH measures. RESULTS: The sample was well distributed across RA severity and SES measures. Contextual and proximate measures of SES were poorly correlated. Lower levels of proximate SES measures (but not contextual) were associated with poorer SRH outcomes. The OLS regressions showed significant associations between the HUI3 and the SF-6D overall scores and the HAQ for self-reported income. The RAQoL did not differ significantly across SES. TSLS regression confirmed the finding that self-reported income was similarly associated with the SRH measures. CONCLUSIONS: Even in a country with universal access to health-care, the impact of a chronic disease such as RA on SRH is associated with self-reported income. The finding that preference-based measures vary with income independently of RA severity could bias economic evaluation.

The systemic lupus erythematosus Tri-nation Study: absence of a link between health resource use and health outcome.

OBJECTIVE: Health consumption and health status in SLE in three countries with different health funding structures were compared. METHODS: Seven hundred and fifteen SLE patients (Canada 231, USA 269, UK 215) were surveyed semi-annually over 4 yr for health resource utilization and health status. Cross-country comparisons of (i) cumulative health expenditure (calculated by applying 2002 Canadian prices to resources in all countries) and (ii) disease damage (Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index, SLICC/ACR DI) at study conclusion were performed after adjustment. Missing expenditure and damage data were managed through multiple imputation using best predictive regressions with all available data from all patients as potential covariates. RESULTS: Four hundred and eighty-five patients provided data at study entry and conclusion and at least four resource questionnaires (Canada 162, USA 157, UK 166); 41 died (Canada 13, USA 18, UK 10); 189 withdrew, were lost to follow-up or provided data at entry and conclusion but fewer than four resource questionnaires (Canada 56, USA 94, UK 39). At conclusion, after imputation, in Canada, the USA and the UK respectively, mean cumulative costs per patient over 4 yr [95% confidence interval (CI)] were $15,845 (13,509, 18,182), $20,244 (17,764, 22,724) and $17,647 (15,557, 19,737) and mean changes in SLICC/ACR DI were 0.49 (0.39, 0.60), 0.63 (0.52, 0.74) and 0.48 (0.39, 0.57). After adjustment for baseline differences, on average (95% CI), Canadian and British patients utilized 20% (8%, 32%) and 13% (1%, 24%) less resources than patients in the USA respectively, but experienced similar health outcomes. CONCLUSION: Despite patients in the USA incurring higher health expenditures, they did not experience superior health outcomes.

Underestimating the value of women: assessing the indirect costs of women with systemic lupus erythematosus. Tri-Nation Study Group.

OBJECTIVE: Indirect costs result from diminished productivity and are incorporated in cost-benefit analysis to guide health resource allocation. Valuing the productivity impairment of those not involved in labor market activities is controversial but important for diseases affecting predominantly women if allocation decisions are to be economically efficient and equitable. We compared indirect costs incurred by women with systemic lupus erythematosus (SLE), a prototypical women's disease, calculated under varying assumptions for the value of diminished labor market and non-labor market activity. METHODS: Six hundred forty-eight female patients with SLE reported on employment status and time lost by themselves and their caregivers from labor market and non-labor market activities over a 6 month period. RESULTS: Average annual indirect costs ranged from $1,424 to $22,604 (1997 Canadian dollars) dependent on the value assigned to labor market and non-labor market activity. CONCLUSION: Indirect cost estimates that fail to consider longterm labor market absenteeism and diminished non-labor market productivity and do not use gender neutral wages to value labor market activity may lead to decisions that jeopardize resources for women's diseases.

Viscosupplementation: therapeutic mechanisms and clinical potential in osteoarthritis of the knee.

Viscosupplementation by means of intra-articular injections of hyaluronic acid has been used to treat osteoarthritis of the knee. The proposed mechanisms of action result from the physical properties of hyaluronic acid, as well as from its anti-inflammatory, anabolic, local analgesic, and chrondroprotective effects. Adverse reactions from hyaluronic acid injections into the knee occurred in 8.3% of the 336 patients treated in one study, but at a rate of less than 3% per injection. Reactions were almost always local and generally resolved over 1 to 2 days. Hyaluronic acid injections were approved by the US Food and Drug Administration as a medical device; thus, the level of efficacy demonstrated is less than might have been required for approval as a drug. Several studies have failed to show statistically significant benefit compared with placebo. Furthermore, the treatment is relatively expensive; the cost of the drug for a series of injections is more than $500 per knee. Therefore, widespread use of these agents should be limited until more convincing data on their efficacy are available from well-designed clinical trials.

The use of alternative medical therapies in patients with systemic lupus erythematosus. Trination Study Group.

OBJECTIVE: As part of an ongoing study of health resource utilization and diminished productivity in patients with systemic lupus erythematosus (SLE), the use of alternative medical therapies was assessed. METHODS: A cohort of 707 patients with SLE from 3 countries completed questionnaires on demographics, social support, health status (using the Short Form 36 health survey), satisfaction with health care, health resource utilization (conventional resources and alternative therapies), and time losses in labor market and non-labor market activities. Annual direct and indirect costs (1997 Canadian dollars) were calculated and compared for users and nonusers of alternative medical therapies. RESULTS: Among the 707 patients, 352 (49.8%) were found to use alternative therapies and at similar rates across Canada, the United States, and the United Kingdom. Users were younger and better educated than nonusers, exhibited poorer levels of self-rated health status and satisfaction with medical care, and had minimal to no objective evidence of worse disease (according to the revised Systemic Lupus Activity Measure instrument). The mean of log direct medical costs for conventional resources was higher for users of select alternative therapies compared with nonusers. In a logistic regression, neither the number of alternative therapies used nor the individual therapy increased the probability of incurring indirect costs. CONCLUSION: The use of alternative medical therapies is common in patients with SLE. Users of many alternative medical therapies accrue greater conventional medical costs compared with nonusers. The use of alternative medical therapy may be a marker for care-seeking behavior associated with higher consumption of conventional medical resources in the absence of demonstrable additional morbidity and should be considered in future cost analyses of patients with SLE.

First lifetime back pain and psychiatry treatment: psychological factors and recovery in compensated workers.

The role of psychological factors in recovery from first lifetime low back pain (LBP) was explored in this study. Consecutive clients from one physiatry clinic in Montreal who had LBP of less than 3 months' duration, were on sick leave and receiving workers' compensation benefits, and reported the current event as first lifetime LBP were enrolled. Psychological factors that fluctuate with current events (Psychiatric Symptom Index) and remain stable over time (General Well Being Scale) were assessed. Outcomes were late return to work (> 31 days) and 1 year incidence of compensated recurrence. Results from two multivariate models indicated lower psychological distress predicted late return to work, and higher well being, higher aggressiveness, and lower anxiety predicted compensated recurrence. Researchers concluded psychological factors do not impact clients with all types of LBP in the same way. For individuals lacking prior LBP experience, better psychological functioning increased lengthy work absence. Thus, awareness of the clients' psychological profiles and previous LBP experiences may benefit recovery.

The needs of patients with arthritis: the patient's perspective.

OBJECTIVE: To identify concerns and learning interests of patients with arthritis. METHODS: A questionnaire was developed, pilot tested, and then used to evaluate 197 patients with arthritis, including osteoarthritis (OA) (n = 41), rheumatoid arthritis (RA) (n = 57), back disease (n = 55), systemic lupus erythematosus (n = 27), and systemic sclerosis (SSc) (n = 17). Twenty concerns and 12 learning interests were rated. Questionnaires were also administered to assess physical disability (Health Assessment Questionnaire), psychological disability (Arthritis Impact Measurement Scales 2), and pain (visual analog scale). Participants addressed accessibility of health services, satisfaction with their physician, psychosocial needs, use of self-help groups, and behavioral strategies used to assist coping. Patients with RA, OA, and back disease, at both a community and a hospital center, were tested to assess whether concerns and learning interests differed based on site of treatment. Analytic methods included analysis of variance, factor analysis, and multiple linear regression. RESULTS: There were no differences in concerns or learning interests based on treatment site. Between diagnostic groups, patients with SSc were more interested in learning about self-help groups. The most frequently reported concern was worsening of the illness. The majority of respondents were interested in learning more about topics that were illness specific. The physician was chosen as the preferred source of information, and the preferred format was in writing. On factor analysis, the 20 concerns were reduced to 5 factors: psychological, coping, medication, social, and financial. Three factors were identified for learning interests: the illness, traditional health management topics, and nontraditional health management topics. Stepwise multiple linear regression revealed predictors for the 5 concern and 3 learning interest factors. The concerns were best predicted by self-reported disease severity, physical disability, and psychological distress, while learning interests were best predicted by self-reported disease severity, pain, and self-help group membership. CONCLUSION: Concerns and learning interests of persons with arthritis did not differ based on the center of treatment or the diagnosis, but can be predicted by the level of pain and simple measures of disability. Better understanding of the relationship between health status and patient-perceived needs will result in improved patient-centered care.

An international perspective on the well being and health care costs for patients with systemic lupus erythematosus. Tri-Nation Study Group.

OBJECTIVE: To compare health care expenditure and health status for patients with systemic lupus erythematosus (SLE) between nations with distinct mechanisms for funding and delivering health care services. METHODS: Seven hundred eight patients with SLE from 2 centers in each of 3 countries (Canada 229, United States 268, United Kingdom 211) underwent physician assessment of disease activity and damage and reported on physical and psychosocial well being, satisfaction, social support, and health resource utilization. To compare overall utilization, constant prices (1997 Canadian dollars) were applied across countries for each service, enabling diverse resources to be collapsed into a single expression. RESULTS: After adjusting for important patient covariates, Canadian, compared to American and British patients, reported significantly superior health status in 3 of 8 Medical Outcome Survey Short Form-36 (SF-36) subscales, the SF-36 physical component summary score, and the visual analog scale of general health status. There was no consistent trend in patient satisfaction. Overall annual resource utilization did not vary significantly, with mean annual per patient expenditures (adjusted for demographics, disease duration, activity, damage, social support, health status, patient satisfaction, and age and sex adjusted country-specific SF-36 general population norms) totalling $4853, $5285, and $4760 for Canada, US, and the UK, respectively. However, within each resource category, differences were observed. Canadians saw more specialists than the British, the British more generalists. Canadians and Americans were more frequent users of the emergency room; Americans of laboratory/imaging procedures. Canadians had higher hospital costs than Americans. CONCLUSION: After adjustment, Canadian patients reported better well being than their counterparts. Despite considerable differences in the mechanisms of health care funding and service mixture, overall resource utilization did not vary significantly between the countries, although there was a trend towards more intense use of inpatient services in Canada and outpatient services in the United States.

Predicting the short term direct medical costs incurred by patients with rheumatoid arthritis.

OBJECTIVE: With increasing interest in revising the mechanisms of health care funding, the ability to anticipate patients' medical expenditures as well as to identify potentially modifiable predictors would be informative for health care providers, payers, and policy makers. METHODS: Eight hundred fifty-eight patients with rheumatoid arthritis from 2 Canadian centers reported semi-annually on their health services utilization and health status for up to 12 years. Annual direct costs were calculated using 1994 Canadian prices. Regression models for the variation in total direct costs and the individual resource components (i.e., physicians, tests, medications, acute and non-acute hospital care) were estimated using previous values of age, sex, disease duration, education, methotrexate availability, employment status, global well being, pain, duration of morning stiffness, and functional disability as predictor variables. The models were developed using all available data except the last 2 observations (i.e., data collected on the last 2 self-report questionnaires) from each patient, which were reserved for model validation. The predictive abilities of the models were assessed by comparing the most recent costs with those predicted by the model using values of the predictor variables from the previous time period. Further, to assess whether the models conferred any advantage over cost estimates based only on previous costs, most recent observed costs were also compared with costs observed in the preceding time period. RESULTS: Self-reported indices of either global well being, pain, or functional disability predicted total direct costs as well as the costs of the 5 individual resource components. Being younger, female, disabled from the work force, having shorter disease duration, and receiving more formal education also predicted higher costs in at least on health resource category. However, being older predicted higher acute and non-acute care hospital costs. Regression models incorporating longitudinal data did not perform better than average costs in the preceding time period in predicting future short term costs. CONCLUSION: Global well being, pain, functional disability, and previous costs are the most important predictors of short term direct medical costs. Although we have demonstrated that regression models do not perform better than previous costs in predicting future short term costs, previous costs are a much less informative predictor than health status variables. Variables such as functional disability and pain identify potentially modifiable disease features and suggest interventions that may improve patient well being and reduce costs.

Direct and indirect medical costs incurred by Canadian patients with rheumatoid arthritis: a 12 year study.

OBJECTIVE: To perform the first prospective longitudinal study of direct (health services utilized) and indirect costs (diminished productivity represented by income loss) incurred by patients with rheumatoid arthritis (RA) in Saskatoon and Montreal, followed for up to 12 and 4 years, respectively. METHODS: 1063 patients reported on health status, health services utilization, and diminished productivity every 6 months. RESULTS: Annual direct costs were $3788 (1994 Canadian dollars) in the late 1980s and $4656 in the early 1990s. Given that the average age exceeded 60 years, few participated in labor force activities or considered themselves disabled from the labor force and their indirect costs were substantially less, $2165 in the late 1980s and $1597 in the early 1990s. Institutional stays and medications made up at least 80% of total direct costs. Lengths of stay in acute care facilities remained constant, but the rate of hospitalization increased in the early 1990s, increasing average hospital costs per patient from $1563 in the late 1980s to $2023 in the early 1990s. For nonacute care facilities, rate of admission as well as length of stay increased over time, increasing costs per patient in Saskatoon 5-fold, from $291 to $1605. Those with greater functional disability incurred substantially higher direct and those under 65 years incurred higher indirect costs. CONCLUSION: Direct costs are higher than indirect costs. The major component is due to institutional stays that, in contrast to other direct cost components, is increased in the older and more disabled. Measures to reduce longterm disability by earlier, more aggressive intervention have the potential to produce considerable cost savings. However, it is unknown which strategies will have the greatest effect on outcome and accordingly, how resources can be optimally allocated.

Back school in a first episode of compensated acute low back pain: a clinical trial to assess efficacy and prevent relapse.

OBJECTIVE: To assess the efficacy of a back school program for patients with a first episode of acute work-related low back pain requiring compensation. DESIGN: A randomized single-blind controlled trial. SETTING: A private physiatrics outpatient clinic. PATIENTS: The mean duration of low back pain was 15 days. INTERVENTION: Eligible patients were randomized to a standard treatment program that included daily physiotherapy (n = 86) or the same program with the addition of back school (n = 82). The back school program consisted of three 90-minute sessions given by a single trained instructor at 0, 1, and 8 weeks. MAIN OUTCOME MEASURES: The primary outcomes were the time off work for the presenting episode of back pain and the number and duration of recurrences in the year following the study onset. Secondary outcomes included the level of pain, spinal mobility, active straight-leg raising, and functional disability assessed by the Oswestry and Roland-Morris scales. RESULTS: Those randomized to the back school group gained significantly more knowledge, based on the multiple choice examination (p = .0001) and performed the exercise program significantly better (p = .0001) than the standard care group. There were no differences between the two treatment groups for either of the primary outcomes. The median time to return to work from randomization was 33 days for both the back school and the standard care groups (p = .48). The number of compensated recurrences of low back pain over 1 year was similar (back school = 14, standard care = 10, p = .16), as was the median duration of these episodes (back school = 25 days, standard care = 70 days, p = .21). There were no significant differences favoring the back school group for any of the secondary outcomes at the posttreatment, 6-month, or 12-month assessments. CONCLUSION: A back school intervention in addition to standard care resulted in no reduction in the time to return to work or the number or duration of recurrences of low back pain requiring compensation over a period of one year.

Why health care costs more in the US: comparing health care expenditures between systemic lupus erythematosus patients in Stanford and Montreal.

OBJECTIVE: Recent studies to identify the causes of higher health care expenditure in the US versus Canada have relied on population-based measures of health care utilization and have restricted their analysis to one sector, such as physician or hospital expenditures. We present a detailed comparative analysis of the direct costs (health services utilized) of treating systemic lupus erythematosus (SLE) patients in Stanford, CA and Montreal, Quebec. METHODS: Using the self-report Stanford Health Assessment Questionnaire, we assessed 6-month direct costs incurred by 174 American and 164 Canadian SLE patients. We explored 3 potential reasons for the differential expenditure. These were 1) higher prices for health care inputs, 2) more severe disease in the patient case mix, and 3) greater resource utilization. RESULTS: The direct health care costs for the American SLE patients exceeded those for the Canadian patients by almost 2-fold ($10,530 versus $5,271, expressed in 1991 US dollars). The higher direct costs were explained by the higher price of health services in the US and the more severe disease mix. In fact, for all health resources categories studies, Canadians utilized at least as many services as their American counterparts. Canadians had longer hospital stays, made more emergency room visits, and used more medications. CONCLUSION: Despite significantly greater per capita health care expenditure in the US, our data show that Canadian SLE patients actually receive more medical services.

Diagnostic accuracy of technologies used in low back pain assessment. Thermography, triaxial dynamometry, spinoscopy, and clinical examination.

STUDY DESIGN: A prospective blind study compared three new technologies to assess back pain. OBJECTIVE: To assess the diagnostic accuracy and comparability of thermography, triaxial dynamometry, and spinoscopy in the assessment of recent onset work-related low back pain. SUMMARY OF BACKGROUND DATA: The role of these technologies in assessing patients with low back pain is unproved. METHODS: Forty-one patients with low back pain and 46 control subjects were assessed by each technology and by two clinical examiners blind to clinical status. Twenty patients were trained to simulate a healthy back without low back pain, and 50% of the control subjects were trained to simulate the presence of a low back pain disorder. Each technology was interpreted on two occasions by each of two readers. RESULTS: Thermography performed significantly worse than did triaxial dynamometry, spinoscopy, and clinical examination. The diagnostic accuracy of the last three was similar, and inter-rater comparability did not differ significantly. Among simulators, the diagnostic accuracy of triaxial dynamometry and spinoscopy was significantly higher than that of clinical examination, although considerable inaccuracy remained in assessing individual subjects. CONCLUSIONS: The diagnostic accuracy of thermography in recent onset low back pain does not support its use. Among those simulating normality or low back pain, triaxial dynamometry and spinoscopy have greater diagnostic accuracy than does a single clinical evaluation. However, for an individual, the inaccuracy that remains limits the use of triaxial dynamometry or spinoscopy for diagnosis in recent onset low back pain.

Decreasing costs and improving outcomes in systemic lupus erythematosus: using regression trees to develop health policy.

OBJECTIVE: To characterize patients with systemic lupus erythematosus (SLE) who are expected to experience the highest direct and indirect monetary costs and greatest diminished productivity so that we may intervene to reduce costs and improve outcomes. METHODS: We assessed demographics and health status in January, 1990 and costs incurred in the last 6 months of 1990 in January, 1991 in 151 patients with SLE enrolled in the Montreal General Hospital Lupus Registry. We used regression trees to separate low from high cost patients. RESULTS: Patients with poor physical or poor psychological functioning incur the highest direct costs (3-fold and 1.6-fold the group mean, respectively); those with the poorest psychological functioning incur the highest indirect costs (2-fold the group average); and those with the most intense pain experience the greatest impairment in productivity (3-fold the group average). CONCLUSION: Targeting patients with poor physical and psychological functioning and substantial pain with appropriate interventions may improve their outcomes and reduce disease costs. Targeting patients expected to have low costs with preventative interventions may delay worse outcomes and reduce future costs.

The impact of disease activity, treatment and disease severity on short-term costs of systemic lupus erythematosus.

OBJECTIVE: To assess the impact of disease activity, current treatment, and global disease severity (or damage) on short-term direct and indirect costs of systemic lupus erythematosus (SLE). METHODS: 150 patients were evaluated twice, one year apart. Disease activity was assessed by the SLE disease activity index, and ordinal scales were used to evaluate treatment (prednisone = 0, 1 to 20 mg/day, > 20 mg/day, and use of immunosuppressive agents) and global disease severity [renal severity = 0 to 3, central nervous system (CNS) severity = 0 to 2, hematologic severity = 0 to 1]. Costs were assessed with the economic portion of the Health Assessment Questionnaire adapted for Canada. RESULTS: Global disease severity was significantly correlated with both direct (p = 0.0001) and indirect (p = 0.02) costs, and current treatment with indirect costs (p = 0.002). The renal and CNS subscales of the global severity measure predicted direct costs (p < 0.01) and the CNS subscale predicted indirect costs (p = 0.002). Stepwise multivariable models selected the global severity index (p = 0.004) as a predictor of direct costs, and either the treatment index (p = 0.02) or the global severity index (p = 0.02) as a predictor of indirect costs. CONCLUSION: The global disease severity index, particularly the subscales involving the renal and CNS organ systems, and the treatment index are predictors of the short-term costs of SLE.

A Canadian study of the total medical costs for patients with systemic lupus erythematosus and the predictors of costs.

OBJECTIVE: We conducted a cost identification analysis on 164 consecutive patients with systemic lupus erythematosus (SLE) who entered the Montreal General Hospital Lupus Registry between January 1977 and January 1990, compared their costs to the population of Quebec, and determined the predictors of cost. METHODS: In January 1990 and 1991, participants completed questionnaires on health services utilization and on employment history over the preceding 6 months, as well as on functional, psychological, and social well-being. The societal burden of SLE was determined in terms of direct costs (all resources consumed in patient care) and indirect costs (wages lost due to lack of work force participation because of morbidity). RESULTS: The mean total annual cost for 1989, as assessed in January 1990 and expressed in 1990 Canadian dollars, was $13,094. Although only 44% of the patients were fully employed, indirect costs were responsible for 54% of this total ($7,071). Ambulatory costs, primarily diagnostic procedures, medications, and visits to health care professionals, comprised 55% of direct costs ($3,331). The results of the 1990 cost determination were similar. On average, hospitalizations among SLE patients were 4 times more frequent than among the general population of Quebec (matched for age and sex), and the number of ambulatory visits to physicians was double that for the average resident of Quebec. Higher 1989 values of creatinine and a poorer level of physical functioning were the best predictors of higher 1990 direct costs (R2 = 0.29). A poorer SLE well-being score, a combination of education and employment status, and a weaker level of social support were the best predictors of higher indirect costs (R2 = 0.29). CONCLUSION: The direct and indirect costs for patients with SLE are substantial, and their respective predictors are distinct. Direct costs arise from organic complications which induce functional disability. Predictors of indirect costs are potentially amenable to psychological or social interventions and may be more easily modified than the determinants of direct costs, thereby improving patient outcome while simultaneously reducing disease costs.