The cost-effectiveness of biologic versus non-biologic treatments and the health-related quality of life among a sample of patients with inflammatory bowel disease in a tertiary care center in Saudi Arabia

Abstract

Aims

This study’s objectives were to examine and compare the cost-effectiveness of biologic and non-biologic therapies in the improvement of the health-related quality of life (HRQoL) of patients with inflammatory bowel disease (IBD) in Saudi Arabia.     

Inflammatory bowel disease: healthcare costs for patients who are adherent or non-adherent with infliximab therapy

Objective:

Healthcare costs of inflammatory bowel disease are substantial. This study examined the effect of adherence versus non-adherence on healthcare costs in patients with inflammatory bowel disease.

Methods:

Adults who started infliximab treatment between 2006 and 2009 and had a diagnosis of inflammatory bowel disease were identified from MarketScan Databases. Medication adherence was defined as an infliximab medication possession ratio of 80% or greater in the first year. Mean treatment effects (adherence versus non-adherence) on costs in adherent patients were estimated with propensity-weighted generalized linear models.

Results:

A total of 1646 patients were identified. Significant variables in the model used to develop propensity weights were age, year of infliximab initiation, having Medicare coverage, presence of supplementary diagnoses, office as the place of service for infliximab initiation, prior aminosalicylate use, prior outpatient costs, number of prior outpatient visits, and number of prior colonoscopies. Mean total costs in adherent (n?=?674) and propensity-weighted non-adherent (n?=?972) patients were $41,713 versus $47,411 overall (p?p?p?p?p?p?=?0.460).

Limitations:

Costs associated with infliximab administration (infusions, adverse events) were captured in healthcare costs (inpatient, outpatient, and emergency room), not in infliximab costs. The influence of adherence on indirect costs (e.g., time lost from work) could not be determined. Reasons for non-adherence were not available in the database.

Conclusions:

In patients who were adherent to infliximab treatment (a medication possession ratio of 80% or greater in the first year), adherence versus non-adherence was associated with lower total healthcare costs, supporting the overall value of infliximab adherence in patients with inflammatory bowel disease.     

Variations in care: a retrospective database analysis of healthcare utilization patterns for patients with inflammatory bowel disease

Abstract

Background:

Biologic therapy has been shown to be effective in achieving and maintaining remission in the treatment of inflammatory bowel disease (IBD). However, their impact on healthcare resource utilization is not well understood. This study explored the impact of biologic use on IBD-related hospital admissions and emergency room visits and healthcare expenditures.

Methods:

This study used a retrospective cohort design to analyze data from the MarketScan Commercial and Medicare databases (Truven Health Analytics Inc.) for the years 2006–2010. Patients were identified using ICD-9 diagnosis codes for IBD and age 18 or older at time of initial diagnosis. Linear models were used to predict the probability of an IBD-related hospitalization or ER visit and healthcare expenditures with binary variables indicating use of biologics in the current year and in the previous 2 years, as well as patient- and area-level control variables.

Results:

Patients using biologics in the current year were 14.1–17.6% more likely to be hospitalized for IBD. However, biologic use in the previous year was associated with a 3.8–5.6% reduction in hospitalizations, and biologic use 2 years prior was associated with a 1–2.8% reduction in hospitalizations in the current year. Similar results are found for ER visits. All indicators for biologic use were associated with increased expenditures.

Conclusions:

There was a negative association between lagged use of biologics and the proportion of patients with IBD-related hospitalizations and ER visits. This finding may suggest that increased use of biologics over time is associated with a decrease in IBD-related healthcare utilization.     

Costs of providing infusion therapy for patients with inflammatory bowel disease in a hospital-based infusion center setting

Aims: Inflammatory bowel disease (IBD) (e.g. ulcerative colitis [UC] and Crohn’s disease [CD]) severely impacts patient quality-of-life. Moderate-to-severe disease is often treated with biologics requiring infusion therapy, adding incremental costs beyond drug costs. This study evaluates US hospital-based infusion services costs for treatment of UC or CD patients receiving infliximab or vedolizumab therapy.

Materials and methods: A model was developed, estimating annual costs of providing monitored infusions using an activity-based costing framework approach. Multiple sources (published literature, treatment product inserts) informed base-case model input estimates.

Results: The total modeled per patient infusion therapy costs in Year 1 with infliximab and vedolizumab was $38,782 and $41,320, respectively, and Year 2+, $49,897 and $36,197, respectively. Drug acquisition cost was the largest total costs driver (90–93%), followed by costs associated with hospital-based infusion provision: labor (53–56%, non-drug costs), allocated overhead (23%, non-drug costs), non-labor (23%, non-drug costs), and laboratory (7–10%, non-drug costs).

Limitations: Limitations included reliance on published estimates, base-case cost estimates infusion drug, and supplies, not accounting for volume pricing, assumption of a small hospital infusion center, and that, given the model adopts the hospital perspective, costs to the patient were not included in infusion administration cost base-case estimates.

Conclusions: This model is an early step towards a framework to fully analyze infusion therapies’ associated costs. Given the lack of published data, it would be beneficial for hospital administrators to assess total costs and trade-offs with alternative means of providing biologic therapies. This analysis highlights the value to hospital administrators of assessing cost associated with infusion patient mix to make more informed resource allocation decisions. As the landscape for reimbursement changes, tools for evaluating the costs of infusion therapy may help hospital administrators make informed choices and weigh trade-offs associated with providing infusion services for IBD patients.     

Health-related quality of life,work productivity and costs related to patients with inflammatory bowel disease in Austria

Abstract

Objective

Inflammatory-Bowel-Disease (IBD) is a lifelong illness with significant impact on health-related quality of life (HRQoL). The disease-burden causes work productivity impairment, such as sick-leave and restriction of leisure time activities. From a societal perspective, productivity loss often contributes significantly to the total costs. The aim of the study is to analyze the impact of disease-burden on work productivity, daily activities, and HRQoL.     

Burden of Crohn’s disease in the United States: long-term healthcare and work-loss related costs

Abstract

Aims

To quantify the long-term direct and indirect costs among patients with Crohn’s disease (CD) and specific subgroups of these patients in the United States from the private payer’s perspective.     

Differences in episode-based care costs for multidetector computed tomographic coronary angiography versus myocardial perfusion imaging for the diagnosis of coronary artery disease

Abstract

Background: Multidetector computed tomography (MDCT) is a novel method for diagnosis and prognosis of coronary artery disease (CAD). The opportunity costs that favour MDCT over other CAD diagnostic methods is currently unknown.

Methods: This study used an episodes of care cost model based on epidemiologic and economic data evaluating individuals without known CAD undergoing MDCT or myocardial perfusion scintigraphy (MPS). It was a multicenter retrospective database review of medical and pharmacy-related claims linked by episodes of care from 2002 to 2005. CAD-related episodes of care costs were examined 1-year downstream for patients after initial MDCT that were matched to patients who underwent MPS.

Results: After adjustment for patient factors, 1-year total CAD-related episodes of care costs for MDCT were 16.4% lower than MPS, by an average of $682 (95% confidence interval $14, $1,350) per patient. While costs per CAD-related episode were similar between MDCT and MPS groups ($4,284 vs. $4,277, p=0.08).

Conclusions: Patients without known CAD who undergo MDCT as an initial diagnostic test, compared to MPS, incurred fewer CAD-related episodes of care and lower overall CAD-related costs.     

Real-world cost of treatment for multiple sclerosis patients initiating and receiving infused disease-modifying therapies per recommended label in the United States

Abstract

Aims: The study evaluated the real-world cost of treatment in multiple sclerosis (MS) patients initiating infused disease-modifying-therapies (DMT) in the United States.

Materials and Methods: This retrospective cohort study using administrative claims data included adult patients with MS initiating index infusion DMT (ocrelizumab (OCR), natalizumab (NTZ) or alemtuzumab (ATZ)) from April 2017–September 2018 with 6-months pre/12-months post-index continuous enrollment. The primary cohort included patients who had prescribed annual dosing visits indicated by the approved product label (PL): 3 OCR, 5 ATZ, and 12–13 NTZ infusion visits within the first year of initiation. Annual treatment cost was the sum of all costs on index DMT infusion visit dates. Costs were summarized for a primary and secondary cohort of patients receiving additional doses than prescribed in PL (>3 OCR, >5 ATZ, and >13 NTZ infusion visits); and an overall cohort of patients who met minimum required annual dose (≥3 OCR, ≥5 ATZ, and ≥12 NTZ), further stratified by insurance type.

Results: For patients in the primary cohort (123 OCR, 18 ATZ, and 48 NTZ), mean (standard-deviation) annual cost of treatment with OCR, ATZ, and NTZ cohorts was $72,066 ($34,480), $121,053 ($51,097) and $93,777 ($38,815), respectively. Among patients initiating OCR and NTZ, 15 and 6% respectively, had additional infusion visits leading to greater costs. Mean annual costs of index infusion DMT treatment in the overall cohort (162 patients treated with OCR, 18 with ATZ, 56 with NTZ) were $80,582, $121,053, and $93,807, respectively. The mean costs for commercial enrollees were higher than those for MAPD enrollees.

Limitations: Small sample size, limited population generalizability, and cost-reduction for ATZ beyond the second year need to be accounted for.

Conclusions: Real-world infusion DMT treatment costs for commercially insured patients were higher than perceived expenditures based on wholesale acquisition cost and administration costs via a physician-fee schedule. Consideration of real-world costs in cost-effectiveness and treatment/coverage decisions is needed.     

Modelling the clinical and economic implications of galantamine in the treatment of mild-to-moderate Alzheimer's disease in Germany

Abstract

Objective:

This analysis was to assess the long-term clinical and economic implications of galantamine in the treatment of mild-to-moderate Alzheimer's disease (AD) in Germany.

Methods:

An economic model was developed using discrete event simulation to predict the course of AD through changes in cognition, behavioural disturbance, and function over time. It compares the costs and benefits of galantamine versus no-drug treatment and ginkgo biloba. Clinical data were mainly derived from analyses of pooled data from clinical trials. Epidemiological and cost data were obtained from literature and public data sources. Costs (2009 euros) from the perspective of the German Statutory Health Insurance were used.

Results:

The mean survival time for the model population is about 3.44 years over 10 years of simulation. Galantamine delays average time to severe stage of the disease by 3.57 and 3.36 months, compared to no-drug treatment and ginkgo biloba, respectively. Galantamine reduces time spent in an institution by 2.34 and 2.21 months versus no-drug treatment and ginkgo biloba, respectively. The use of galantamine is projected to yield net savings of €3,978 and €3,972 per patient versus no-drug and ginkgo biloba treatments. These results, however, may be limited by lack of long-term comparative efficacy data as well as data on long-term care costs based on multiple outcome measures.

Conclusion:

Compared to no-drug treatment and ginkgo biloba, galantamine therapy provides clinical benefits and achieves savings in healthcare costs associated with care for patients with mild-to-moderate AD in Germany.     

Cost-utility analysis of levodopa carbidopa intestinal gel (Duodopa) in the treatment of advanced Parkinson’s disease in patients in Scotland and Wales

Aims: To carry out a cost-utility analysis comparing the cost-effectiveness of levodopa carbidopa intestinal gel (LCIG) with standard of care (SOC) in patients with advanced Parkinson’s Disease (aPD) unsuitable for apomorphine or deep brain stimulation (DBS). LCIG is the only treatment option in this small, but clinically important, population.

Methods: A Markov model with 25 disease states based on disease stage and off-time status plus death. Patients enter the model with aPD spending >50% of their waking day in the off-state. Patients progress through the model in 6-monthly cycles for 20 years to approximate lifetime treatment and capture long-term costs and effects of therapy. Inputs are based on LCIG clinical trials for clinical outcomes and health state utilities, the literature for health state transitions and use UK-based input data wherever possible (drug costs, disease/adverse event management costs, discontinuation rates, mortality rates).

Limitations: Data collection can be challenging in this small, elderly population with advanced disease, therefore some model inputs were estimated, rather than collected directly. It was assumed that a reduction in off-time was the only benefit after the first year of treatment with LCIG; this is a conservative approach, since there may be additional clinical benefits.

Results: There is a considerable incremental gain in quality adjusted life years (QALYs) for patients treated with LCIG of 1.26 QALY with an associated incremental cost-effectiveness ratio (ICER) of £52,110. If the impact on caregivers is included, the ICER reduces to £47,266.

Conclusions: In cases where there is an orphan population, with no alternative treatment options, HTA assessments have a broader decision-making framework and the ICER is interpreted in this context. In the setting of a very small population, with considerable unmet need, LCIG represents value for money, as reflected by funding approval across the UK.     

Real-world comparison of hospitalization costs for heart failure in type 2 diabetes mellitus patients with established cardiovascular disease treated with canagliflozin versus other antihyperglycemic agents

Abstract

Aims: This real-world study compared hospitalization for heart failure (HHF) costs and all-cause healthcare costs in patients with type 2 diabetes mellitus (T2DM) and established cardiovascular disease treated with the sodium glucose co-transporter 2 inhibitor (SGLT2i) canagliflozin and non-SGLT2i antihyperglycemic agents (AHAs).

Materials and methods: Propensity score-matched cohorts from a retrospective observational study (OBSERVE-4D) using the Truven MarketScan Commercial Claims and Encounters and Optum Clinformatics databases were analyzed. HHF and all-cause healthcare costs per-patient-per-month (PPPM) were compared for patients initiated on canagliflozin and non-SGLT2i AHAs in the on-treatment analysis.

Results: Baseline characteristics were well balanced between matched cohorts that included new users of canagliflozin or non-SGLT2i AHAs in the Truven (13,954 and 45,101, respectively) and Optum (11,490 and 53,360, respectively) databases. The mean (95% CI) PPPM cost of HHF was lower for canagliflozin than for non-SGLT2i AHAs in analyses of both the Truven ($21.31 [$21.25, $21.37]) and Optum ($30.43 [$30.41, $30.45]) databases. The mean (95% CI) PPPM all-cause healthcare cost was also lower for canagliflozin than for non-SGLT2i AHAs in analyses of both the Truven ($321 [$280, $361]) and Optum ($449 [$402, $495]) databases.

Limitations: This study is subject to the limitations inherent to observational research including potential for coding errors and biases and unobserved confounding. Because all patients were in commercially administered health plans, these findings cannot be easily generalized to uninsured or Medicaid populations. Patient costs were evaluated up to and including their first HHF event. Post-discharge costs such as the costs of subsequent rehospitalizations were not included in this analysis.

Conclusions: For patients with T2DM and established cardiovascular disease in this real-world study, treatment with canagliflozin was associated with lower HHF costs and all-cause healthcare costs compared with treatment with non-SGLT2i AHAs.     

Retrospective database analysis of healthcare resource utilization and costs in patients who develop post-transplant lymphoproliferative disease within the first year following allogeneic hematopoietic stem cell transplants

Abstract

Aims

Healthcare resource utilization (HRU) and costs in post-transplant lymphoproliferative disease (PTLD) patients following allogeneic hematopoietic stem cell transplant (HCT) were evaluated in the USA.     

Budget impact analysis of demineralized bone matrix in combination with autograft in lumbar spinal fusion procedures for the treatment of lumbar degenerative disc disease in Spain

Objective: To estimate the budget impact (BI) of introducing local autograft (LA) combined with demineralized bone matrix (LA?+?DBM) in lumbar spinal fusion (LSF) procedures to treat lumbar degenerative disc disease (LDDD) in Spain.

Methods: A decision tree model was developed to evaluate the 4-year BI associated with introducing LA?+?DBM putty to replace currently available grafting methods, including iliac crest bone graft (ICBG), LA alone, and LA combined with beta-tricalcium phosphate (LA?+?ceramics), with 30%, 40%, and 30% market shares, respectively. The analysis was conducted for a hypothetical cohort of 100 patients with LDDD receiving LSF, assuming LA?+?DBM would replace 100% of the standard of care mix. The fusion rates extracted from the literature were validated by an expert panel. Costs (€2017) were obtained from different Spanish sources. Budget impact and incremental cost per successful fusion were calculated from the perspective of the Spanish National Health System (NHS).

Results: Over 4 years, replacing currently available options with LA?+?DBM for 100 patients resulted in an additional cost of €12,330 (€123/patient), and an additional 14 successful fusions, implying a cost of €881 per additional successful fusion. When costs of productivity loss were included, the introduction of LA?+?DBM resulted in cost savings of €70,294 (€703/patient).

Limitations: The lack of high-quality, homogeneous, head-to-head research studying the efficacy of grafting procedures available to patients undergoing LSF, in addition to a lack of long-term follow-up in existing studies. Therefore, the number of fusions occurring within the model’s time horizon may be underestimated.

Conclusions: Acquisition costs of DBM were partially offset by costs of failed fusions, adverse events and reoperation when switching 100 hypothetical LDDD patients undergoing LSF procedures from standard of care grafting methods to LA?+?DBM from the perspective of the Spanish NHS. DBM cost was entirely offset when costs of lost productivity were considered.     

Costs of inpatient and emergency department care for chronic obstructive pulmonary disease in an elderly Medicare population

Objective:

Treatment in the hospital setting accounts for the largest portion of healthcare costs for COPD, but there is little information about components of hospital care that contribute most to these costs. The authors determined the costs and characteristics of COPD-related hospital-based healthcare in a Medicare population.

Methods

Using administrative data from 602 hospitals, 2008 costs of COPD-related care among Medicare beneficiaries age ≥65 years were calculated for emergency department (ED) visits, simple inpatient admissions and complex admissions (categorized as intubation/no intensive care, intensive care/no intubation, and intensive care/intubation) in a cross-sectional study. Rates of death at discharge and trends in costs, length of stay and readmission rates from 2005 to 2008 also were examined.

Main results:

There were 45,421 eligible healthcare encounters in 2008. Mean costs were $679 (SD, $399) for ED visits (n = 10,322), $7,544 ($8,049) for simple inpatient admissions (n = 25,560), and $21,098 ($46,160) for complex admissions (n = 2,441). Intensive care/intubation admissions (n = 460) had the highest costs ($45,607, SD $94,794) and greatest length of stay (16.3 days, SD 13.7); intubation/no ICU admissions had the highest inpatient mortality (42.1%). In 2008, 15.4% of patients with a COPD-related ED visit had a repeat ED visit and 15.5–16.5% of those with a COPD-related admission had a readmission within 60 days. From 2005 to 2008, costs of admissions involving intubation increased 10.4–23.5%. Study limitations include the absence of objective clinical data, including spirometry and smoking history, to validate administrative data and permit identification of disease severity.

Conclusions:

In this Medicare population, COPD exacerbations and related inpatient and emergency department care represented a substantial cost burden. Admissions involving intubation were associated with the highest costs, lengths of stay and inpatient mortality. This population needs to be managed and treated adequately in order to prevent these severe events.     

Modelling the cost-effectiveness of nevirapine triple combination therapy and dual combination therapy for the treatment of HIV disease in the United Kingdom

Summary

Recent advances in HIV antiretroviral therapy together with limited budgets have forced payers to look for evidence that new combinations provide good value for money. Using a public financing perspective, two Markov models are employed to evaluate the first-year outcomes and costs and the long-term cost-effectiveness of adding nevirapine (NVP) to dual combination therapy with zidovudine (ZDV) and didanosine (ddI) in the United Kingdom.

First-year medical care savings are estimated to be £2,122 (103.8% of NVP cost). In the longer term, NVP/ZDV/ddI therapy yields £6,186 per life year saved (costs discounted at 6%). The model is moderately sensitive only to duration of therapy effects and the therapy initiation time. These model estimates suggest that policy makers may expect to observe superior initial health outcomes and substantial medical cost savings during the first year of therapy, as well as acceptable long-term cost-effectiveness, when NVP/ZDV/ddI is used in place of dual therapy.     

Estimated burden of cardiovascular disease and value-based price range for evolocumab in a high-risk,secondary-prevention population in the US payer context

Aim: To estimate real-world cardiovascular disease (CVD) burden and value-based price range of evolocumab for a US-context, high-risk, secondary-prevention population.

Materials and methods: Burden of CVD was assessed using the UK-based Clinical Practice Research Datalink (CPRD) in order to capture complete CV burden including CV mortality. Patients on standard of care (SOC; high-intensity statins) in CPRD were selected based on eligibility criteria of FOURIER, a phase 3 CV outcomes trial of evolocumab, and categorized into four cohorts: high-risk prevalent atherosclerotic CVD (ASCVD) cohort (n?=?1448), acute coronary syndrome (ACS) (n?=?602), ischemic stroke (IS) (n?=?151), and heart failure (HF) (n?=?291) incident cohorts. The value-based price range for evolocumab was assessed using a previously published economic model. The model incorporated CPRD CV event rates and considered CV event reduction rate ratios per 1?mmol/L reduction in low-density lipoprotein-cholesterol (LDL-C) from a meta-analysis of statin trials by the Cholesterol Treatment Trialists Collaboration (CTTC), i.e. CTTC relationship.

Results: Multiple-event rates of composite CV events (ACS, IS, or coronary revascularization) per 100 patient-years were 12.3 for the high-risk prevalent ASCVD cohort, and 25.7, 13.3, and 23.3, respectively, for incident ACS, IS, and HF cohorts. Approximately one-half (42%) of the high-risk ASCVD patients with a new CV event during follow-up had a subsequent CV event. Combining these real-world event rates and the CTTC relationship in the economic model, the value-based price range (credible interval) under a willingness-to-pay threshold of $150,000/quality-adjusted life-year gained for evolocumab was $11,990 ($9,341–$14,833) to $16,856 ($12,903–$20,678) in ASCVD patients with baseline LDL-C levels ≥70?mg/dL and ≥100?mg/dL, respectively.

Conclusion: Real-world CVD burden is substantial. Using the observed CVD burden in CPRD and the CTTC relationship, the cost-effectiveness analysis showed that, accounting for uncertainties, the expected value-based price for evolocumab is higher than its current annual cost, as long as the payer discount off list price is greater than 20%.     

Cost-effectiveness of dipeptidyl peptidase-4 inhibitor monotherapy versus sulfonylurea monotherapy for people with type 2 diabetes and chronic kidney disease in Thailand

Objective: With a high prevalence of chronic kidney disease (CKD) in type 2 diabetes (T2DM) in Thailand, the appropriate treatment for the patients has become a major concern. This study aimed to evaluate long-term cost-effective of dipeptidyl peptidase-4 (DPP-4) inhibitor monothearpy vs sulfonylurea (SFU) monotherapy in people with T2DM and CKD.

Methods: A validated IMS CORE Diabetes Model was used to estimate the long-term costs and outcomes. The efficacy parameters were identified and synthesized using a systematic review and meta-analysis. Baseline characteristics and cost parameters were obtained from published studies and hospital databases in Thailand. Costs were expressed in 2014?US Dollars. Outcomes were presented as an incremental cost-effectiveness ratio (ICER). One-way and probabilistic sensitivity analyses were performed to estimate parameter uncertainty.

Results: From a societal perspective, treatment with DPP-4 inhibitors yielded more quality-adjusted life years (QALYs) (0.024) at a higher cost (>66,000 Thai baht (THB) or >1,829.27 USD) per person than SFU, resulting in the ICER of >2.7 million THB/QALY (>74,833.70 USD/QALY). The cost-effectiveness results were mainly driven by differences in HbA1c reduction, hypoglycemic events, and drug acquisition cost of DPP-4 inhibitors. At the ceiling ratio of 160,000 THB/QALY (4,434.59 USD/QALY), the probability that DPP-4 inhibitors are cost-effective compared to SFU was less than 10%.

Conclusions: Compared to SFU, DPP-4 inhibitor monotherapy is not a cost-effective treatment for people with T2DM and CKD in Thailand.     

Burden of illness for patients with non-dialysis chronic kidney disease and anemia in the United States: review of the literature

Objective: To assess the health-related quality of life (HRQL) and economic burden of chronic kidney disease (CKD) related anemia in non-dialysis patients in the United States (US) via literature review.

Methods: MEDLINE, EMBASE, PROQOLID, and Cochrane Library/Renal Group Resources were searched. Studies were appraised for patient populations, disease-specific versus generic HRQL assessments, and type and magnitude of health-related costs.

Results: The treatment costs for CKD patients with anemia compared to those without anemia were significantly higher and were blunted but persistent after controlling for comorbidities and confounders. Intervention with erythropoiesis stimulating agents (ESA) decreased anemia and avoided hospital admissions. Costs were higher when anemia was poorly controlled or untreated. HRQL burden was mainly due to physical limitations and difficulty in ability to perform activities of daily living. Significant positive correlations between increases in hemoglobin levels and HRQL measures were reported.

Conclusions: Although evidence is limited, the economic and HRQL burden of non-dialysis CKD-related anemia is substantial. Under-treatment of anemia may contribute to higher resource consumption and higher costs; however, patient co-morbidities, use of erythropoietin-stimulating agents, and overall management introduce potential confounds. The contribution of anemia to humanistic disease burden is due to a constellation of factors, including physical activity and functional status.