Epidemiology, Treatment Patterns, and Healthcare Resource Utilization Study of Patients With Alopecia Areata in Taiwan's National Health Insurance Research Database.

OBJECTIVES: This study investigated the epidemiology, treatment patterns, and resource utilization in patients with alopecia areata (AA) in Taiwan using the National Health Insurance Research Database. AA severity was determined by treatment use and diagnostic codes in the year after enrollment (including corticosteroids, systemic immunosuppressants, topical immunotherapy, and phototherapy). METHODS: The cross-sectional analysis was conducted to estimate the incidence and prevalence of AA from 2016 to 2020. For the longitudinal analysis, 2 cohorts were identified: mild/moderate and severe. The cohorts were matched based on age, gender, and comorbidities. Patients were enrolled upon their first claim with an AA diagnosis during the index period of 2017-2018. RESULTS: The number of patients with AA increased from 3221 in 2016 to 3855 in 2020. The longitudinal analysis identified 1808 mild/moderate patients and 452 severe patients. Mild/moderate patients used higher levels of topical corticosteroids (82.41%) than severe patients (73.45%). Conversely, severe patients used more topical nonsteroids (41.81%) and systemic therapies (51.77%) than mild/moderate patients (0.44% and 16.15%, respectively). Oral glucocorticoids use was higher in severe patients (47.57%) relative to mild/moderate patients (14.88%), whereas the use of injectable forms was similar. The most used systemic immunosuppressants were methotrexate, cyclosporin, and azathioprine. Topical immunotherapy utilization decreased with subsequent treatment lines for severe patients. Treatment persistence at 6 months was low for all treatments. Severe patients had higher annual AA-related outpatient visits than the mild/moderate cohort. CONCLUSIONS: These findings highlight the need for additional innovations and therapies to address the clinical and economic burden of AA.

Patient Characteristics, Treatment Patterns, Healthcare Resource Utilization, and Costs of Targeted Therapy-Eligible Atopic Dermatitis Patients in Taiwan-A Real-World Study.

INTRODUCTION: The objective of this study was to conduct a retrospective analysis to understand the patient profile, treatment patterns, healthcare resource utilization, and cost of atopic dermatitis (AD) of patients eligible for targeted therapy in Taiwan. METHODS: A retrospective, claims-based analysis was undertaken using Taiwan's National Health Insurance Research Database from 01 January 2014 to 31 December 2017. Patients aged ≥ 2 years and with at least one diagnosis code for AD during 2015 were identified. Patients with comorbid autoimmune diseases were excluded. Enrolled AD patients were categorized using claims-based treatment algorithms by disease severity and their eligibility for targeted therapy treatment. A cohort of targeted therapy-eligible patients was formed, and a matched cohort using patients not eligible for targeted therapy was derived using propensity score matching based on age, gender, and the Charlson Comorbidity Index (CCI). Treatment patterns, resource utilization, and costs were measured during a 1-year follow-up period. RESULTS: A total of 377,423 patients with AD were identified for this study. Most patients had mild AD (84.5%; n = 318,830) with 11.9% (n = 45,035) having moderate AD, and 3.6% (n = 13,558) having severe AD. Within the 58,593 moderate-to-severe AD patients, 1.5% (n = 897) were included in the targeted therapy-eligible cohort. The matched cohort consisted of 3558 patients. During the 1-year follow-up period, targeted therapy-eligible patients utilized antihistamines (85.5%), topical treatments (80.8%), and systemic anti-inflammatories (91.6%) including systemic corticosteroids (51.4%) and azathioprine (59.1%). During the first year of follow-up, targeted therapy-eligible patients (70.5%; 7.01 [SD = 8.84] visits) had higher resource utilization rates and frequency of AD-related outpatient visits compared with the matched cohort (40.80%; 1.85 [SD = 4.71] visits). Average all-cause direct costs during 1-year follow-up were $2850 (SD = 3629) and $1841 (SD = 6434) for the eligible targeted therapy and matched cohorts, respectively. AD-related costs were 17.7% ($506) of total costs for the targeted therapy eligible cohort and 2.2% ($41) for the matched cohort. CONCLUSIONS: AD patients eligible for targeted therapy in Taiwan experienced high resource and economic burden compared with their non-targeted-therapy-eligible counterparts.

The Cost-Effectiveness of 13-Valent Pneumococcal Conjugate Vaccine in Seven Chinese Cities.

Objective: This study estimates the cost-effectiveness of vaccination with the 13-valent pneumococcal conjugate vaccine (PCV13) among infants in Beijing, Shanghai, Shenzhen, Chengdu, Karamay, Qingdao, and Suzhou. Methods: A previously published cost-effectiveness model comparing vaccination with PCV13 to no vaccination was localized to the included Chinese cities. A systematic literature review was undertaken to identify age-specific incidence rates for pneumococcal bacteremia, pneumococcal meningitis, pneumonia, and otitis media (AOM). Age-specific direct medical costs of treating the included pneumococcal diseases were taken from the Chinese Health Insurance Association database. The base case analysis evaluated vaccine efficacy using direct effect and indirect effects (DE+ IDE). A subsequent scenario analysis evaluated the model outcomes if only DE was considered. A vaccination rate of 70% was used. The model reported outcomes over a one-year period after it was assumed the vaccine effects had reached a steady state (5-7 years after vaccine introduction) to include the direct and indirect effects of vaccination. Health outcomes were discounted at 5% during the steady-state period. Results: Vaccination with PCV13 was cost-effective in the base case analysis for all included cities with the incremental cost-effectiveness ratio (ICER) ranging from 1145 CNY(Shenzhen) to 15,422 CNY (Qingdao) per quality-adjusted life-year (QALY) gained. PCV13 was the dominant strategy in Shanghai with lower incremental costs and higher incremental QALYs. PCV13 remained cost-effective in the DE-only analysis with all ICERs falling below a cost-effectiveness threshold of three times GDP per capita in each city. Conclusions: Vaccination with PCV13 was a cost-effective strategy in the analyzed cities for both the DE-only and DE + IDE analyses. PCV13 became very cost-effective when a vaccination rate was reached where IDE is observed.

Relationship between transfusion burden, healthcare resource utilization, and complications in patients with beta-thalassemia in Taiwan: A real-world analysis.

BACKGROUND: This study utilized a population-based claims database to identify patients with beta-thalassemia and evaluate associations between transfusion burden, healthcare resource utilization (HCRU), and complications. STUDY DESIGN AND METHODS: Taiwan's National Health Insurance Research Database was used to identify patients with beta-thalassemia (ICD-10 D56.1) in 2016. Patients with a beta-thalassemia claim in 2016 were indexed into the study at their first claim on or after January 1, 2001 in the dataset through to December 31, 2016 and followed until the end of study. During the follow-up period, red blood cell transfusion (RBCT) units, HCRU, iron chelation therapy use, and beta-thalassemia-related complications incidence were recorded. Patients were grouped into transfusion burden severity cohorts based on average number of RBCT units per 12 weeks during follow-up: 0 RBCT units, >0 to <6 RBCT units (mild), ≥6 to <12 RBCT units (moderate), and ≥12 RBCT units (severe). RESULTS: A total of 2984 patients were included with mean follow-up of 6.95 years. Of these, 1616 (54.2%) patients had no claims for RBCT units, 1112 (37.3%) had claims for >0 to <6 RBCT units, 112 (3.8%) for ≥6 to <12 RBCT units, and 144 (4.8%) for ≥12 RBCT units per 12 weeks. Transfused patients had significantly more all-cause HCRU and iron chelation therapy compared with non-transfused patients during follow-up. Thalassemia-related HCRU and risk of liver, endocrine, cardiac, and renal complications were significantly and positively correlated with increases of RBCT units. DISCUSSION: Clinical and healthcare resource burden of patients with beta-thalassemia is closely related to transfusion burden.

Understanding the global measurement of willingness to pay in health.

Objective: To understand the different methodologies used to elicit willingness to pay for health and the value of a statistical life year through surveys. Methodology: A systematic review of the literature was undertaken to identify studies using surveys to estimate either willingness to pay for health or the value of a statistical life year. Each study was reviewed and the study setting, sample size, sample description, survey administration (online or face to face), survey methodology, and results were extracted. The results of the studies were then compared to any published national guidelines of cost-effectiveness thresholds to determine their accuracy. Results: Eighteen studies were included in the review with 15 classified as willingness to pay and 3 value of a statistical life. The included studies covered Asia (n = 6), Europe (n = 4), the Middle East (n = 1), and North America (n = 5), with one study taking a global perspective. There were substantial differences in both the methodologies and the estimates of both willingness to pay and value of a statistical life between the different studies. Conclusion: Different methods used to elicit willingness to pay and the value of a statistical life year resulted in a wide range of estimates.

Tumor treating fields and maintenance temozolomide for newly-diagnosed glioblastoma: a cost-effectiveness study.

Purpose: The EF-14 trial demonstrated that adding tumor treating fields (TTFields) to maintenance temozolomide (TMZ) significantly extends progression-free survival (PFS) and overall survival (OS) for newly-diagnosed glioblastoma (GBM) patients. This study assessed the cost-effectiveness of TTFields and TMZ for newly-diagnosed GBM from the US healthcare system perspective. Methods and materials: Outcomes for newly-diagnosed GBM patients were estimated over a lifetime horizon using an area under the curve model with three states: stable disease, progressive disease, or death. The survival model integrated the 5-year EF-14 trial results with long-term GBM epidemiology data and US background mortality rates. Adverse event rates were derived from the EF-14 trial data. Utility values to determine quality-adjusted life-years, adverse event costs, and supportive care costs were obtained from published literature. A 3% discount rate was applied to future costs and outcomes. One-way and probabilistic sensitivity analyses were performed to assess result uncertainty due to parameter variability. Results: Treatment with TTFields and TMZ was estimated to result in a mean increase in survival of 1.25 life years (95% credible range [CR] = 0.89-1.67) and 0.96 quality-adjusted life years (QALYs) (95% CR = 0.67-1.30) compared to treatment with TMZ alone. The incremental total cost was $188,637 (95% CR = $145,324-$225,330). The incremental cost-effectiveness ratio (ICER) was $150,452 per life year gained and $197,336 per QALY gained. The model was most sensitive to changes in the cost of TTFields treatment. Conclusions: Adding TTFields to maintenance TMZ resulted in a substantial increase in the estimated mean lifetime survival and quality-adjusted survival for newly-diagnosed GBM patients. Treatment with TTFields can be considered cost-effective within the reported range of willingness-to-pay thresholds in the US.

Estimating the cost-effectiveness of an infant 13-valent pneumococcal conjugate vaccine national immunization program in China.

BACKGROUND: The burden of pneumococcal disease in China is high, and a 13-valent pneumococcal conjugate vaccine (PCV13) recently received regulatory approval and is available to Chinese infants. PCV13 protects against the most prevalent serotypes causing invasive pneumococcal disease (IPD) in China, but will not provide full societal benefits until made broadly available through a national immunization program (NIP). OBJECTIVE: To estimate clinical and economic benefits of introducing PCV13 into a NIP in China using local cost estimates and accounting for variability in vaccine uptake and indirect (herd protection) effects. METHODS: We developed a population model to estimate the effect of PCV13 introduction in China. Modeled health states included meningitis, bacteremia, pneumonia (PNE), acute otitis media, death and sequelae, and no disease. Direct healthcare costs and disease incidence data for IPD and PNE were derived from the China Health Insurance and Research Association database; all other parameters were derived from published literature. We estimated total disease cases and associated costs, quality-adjusted life years (QALYs), and deaths for three scenarios from a Chinese Payer Perspective: (1) direct effects only, (2) direct+indirect effects for IPD only, and (3) direct+indirect effects for IPD and inpatient PNE. RESULTS: Scenario (1) resulted in 370.3 thousand QALYs gained and 12.8 thousand deaths avoided versus no vaccination. In scenarios (2) and (3), the PCV13 NIP gained 383.2 thousand and 3,580 thousand QALYs, and avoided 13.1 thousand and 147.5 thousand deaths versus no vaccination, respectively. In all three scenarios, the vaccination cost was offset by cost reductions from prevented disease yielding net costs of ¥29,362.32 million, ¥29,334.29 million, and ¥13,524.72 million, respectively. All resulting incremental cost-effectiveness ratios fell below a 2x China GDP cost-effectiveness threshold across a range of potential vaccine prices. DISCUSSION: Initiation of a PCV13 NIP in China incurs large upfront costs but is good value for money, and is likely to prevent substantial cases of disease among children and non-vaccinated individuals.

Estimating the response and economic burden of rheumatoid arthritis patients treated with biologic disease-modifying antirheumatic drugs in Taiwan using the National Health Insurance Research Database (NHIRD).

BACKGROUND: Previous studies in Taiwan utilizing the Taiwan's National Health Insurance Database (NHIRD) have estimated the direct healthcare costs of RA patients, but they have not focused on patients on bDMARDs, or considered patients' response to therapy. OBJECTIVES: The objective of this study was to estimate the rate of inadequate response for patients newly treated with biologic disease-modifying antirheumatic drugs (bDMARDs) as well as their costs and resource use. METHODS: Data were from the catastrophic illness file within the NHIRD from 1/1/2009 to 12/31/2013. Patients with RA, which was categorized by the presence of a catastrophic illness card, that were previously bDMARD-naïve, were included in this study if they initiated their first bDMARD during the index period. The index period included all of 2010, a pre-index period consisting of the index date- 365 days, and a follow-up period including the index date to 365 days post-index, were also included. Previously biologically-naïve patients were indexed into the study on the date of their first claim for a bDMARD. A validated algorithm was used to examine the rate of inadequate response (IR) in the biologically-naïve cohort of patients. Inadequate responders met one or more of the following criteria during their year of follow-up: low adherence (proportion of days covered <0.80); switched to or added a second bDMARD; added a new conventional synthetic DMARD (csDMARD); received ≥1 glucocorticoid injection; or increased oral glucocorticoid dosing. All-cause mean annual direct costs and resource use were measured in the year of follow-up. Costs were converted from NT$ to USD using 1 NT$ = 0.033 USD. RESULTS: A total of 818 patients with RA initiated their first bDMARD (54% etanercept and 46% adalimumab) in 2010. After one year of follow-up, 32% (n = 258) were classified as stable, 66% (n = 540) had an IR, and 2% (n = 20) were lost to follow-up. During the follow-up period mean annual total direct costs were $16,136 for stable patients compared to $14,154 for patients with IR. Mean annual non-medication direct costs were $937 for stable patients and $1,574 for patients with IR. Mean annual hospitalizations were higher for patients with IR (0.46) compared to stable patients (0.10) during the one year follow-up period. CONCLUSIONS: The majority of patients that were previously naïve to bDMARDs had an IR to their first bDMARD during the year of follow-up. Patients with an IR had numerically increased all-cause resource utilization and non-medication costs during the follow-up period compared to patients with stable disease. This level of IR suggests an unmet need in the RA treatment paradigm.

Precision Health Economics and Outcomes Research to Support Precision Medicine: Big Data Meets Patient Heterogeneity on the Road to Value.

The "big data" era represents an exciting opportunity to utilize powerful new sources of information to reduce clinical and health economic uncertainty on an individual patient level. In turn, health economic outcomes research (HEOR) practices will need to evolve to accommodate individual patient-level HEOR analyses. We propose the concept of "precision HEOR", which utilizes a combination of costs and outcomes derived from big data to inform healthcare decision-making that is tailored to highly specific patient clusters or individuals. To explore this concept, we discuss the current and future roles of HEOR in health sector decision-making, big data and predictive analytics, and several key HEOR contexts in which big data and predictive analytics might transform traditional HEOR into precision HEOR. The guidance document addresses issues related to the transition from traditional to precision HEOR practices, the evaluation of patient similarity analysis and its appropriateness for precision HEOR analysis, and future challenges to precision HEOR adoption. Precision HEOR should make precision medicine more realizable by aiding and adapting healthcare resource allocation. The combined hopes for precision medicine and precision HEOR are that individual patients receive the best possible medical care while overall healthcare costs remain manageable or become more cost-efficient.

Estimating the Economic Burden of Rheumatoid Arthritis in Taiwan Using the National Health Insurance Database.

BACKGROUND: Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by inflammation and destruction of the joints. OBJECTIVES: This research aims to estimate the economic burden of RA in Taiwan. METHODS: The National Health Insurance Research Database (NHIRD), a claims-based dataset encompassing 99 % of Taiwan's population, was applied. We used a micro-costing approach for direct healthcare costs and indirect social costs by estimating the quantities and prices of cost categories. Direct costs included surgeries, hospitalizations, medical devices and materials, laboratory tests, and drugs. The costs and quantities of the direct economic burden were calculated based on 2011 data of NHIRD. We identified RA patients and a control cohort matched 1:4 on demographic and clinical covariates to calculate the incremental cost related to RA. Indirect costs were evaluated by missed work (absenteeism) and worker productivity (presenteeism). For the indirect burden, we estimated the rate of absenteeism and presenteeism from a patient survey. Costs were presented in US dollars (US$1 = 30 TWD). RESULTS: A total of 41,269 RA patients were included in the database with incremental total direct cost of US$86,413,971 and indirect cost of US$138,492,987. This resulted in an average incremental direct cost of US$2050 per RA patient. Within direct costs, the largest burdens were associated with drugs (US$73,028,944), laboratory tests (US$6,132,395), and hospitalizations (US$3,208,559). For indirect costs, absenteeism costs and presenteeism costs were US$16,059,681 and US$114,291,687, respectively. CONCLUSIONS: The economic burden of RA in Taiwan is driven by indirect healthcare costs, most notably presenteeism.

The Cost-Effectiveness of Pregabalin Versus Gabapentin for Peripheral Neuropathic Pain (pNeP) and Postherpetic Neuralgia (PHN) in China.

INTRODUCTION: Postherpetic neuralgia (PHN), a type of peripheral neuropathic pain (pNeP), is the most common complication of herpes zoster. The objective of this analysis was to determine the cost-effectiveness of pregabalin compared with gabapentin in pNeP and PHN in China. METHODS: We developed a China-localized 12-week simulation model to determine the cost-effectiveness of pregabalin compared to gabapentin in 1000 patients with pNeP and PHN. We utilized a questionnaire of Chinese key opinion leaders to estimate the pre-treatment distribution of pain scores for pNeP and PHN. Treatment outcomes for pregabalin and gabapentin were acquired from the published literature. RESULTS: Treatment with pregabalin lead to 12-week decreases in pain scores of 0.6 (pNeP) and 0.7 (PHN) when compared to patients receiving gabapentin, at an incremental cost per additional day of mild/no pain of $45. The difference in mean days of no or mild pain, moderate pain, and severe pain was 8.8, -5.7, and -3.1, when comparing pregabalin and gabapentin, respectively. Pregabalin had more mean days with a >30% (7.71 days), 40% (8.97 days), and 50% reduction (9.97 days) in pain when compared with gabapentin. In the pNeP scenario, pregabalin was associated with a lower average pain score compared with gabapentin (3.91 vs. 4.55). The difference in mean days of no or mild pain, moderate pain, and severe pain was 9.39, -5.56, and -3.82, when comparing pregabalin and gabapentin, respectively. Pregabalin had more mean days with a >30% (8.77 days), 40% (9.81 days), and 50% reduction (10.55 days) in pain when compared with gabapentin. CONCLUSION: Pregabalin is an effective treatment for PHN and even for pNeP extensively, but at increased cost. It leads to improved outcomes including lower pain scores and more days with no or mild pain. FUNDING: Pfizer, China.

Estimating the cost-effectiveness of linezolid for the treatment of methicillin-resistant Staphylococcus aureus nosocomial pneumonia in Taiwan.

BACKGROUND/PURPOSE: Methicillin-resistant Staphylococcus aureus (MRSA) nosocomial pneumonia (NP) is associated with higher resource utilization, increased hospital stays, and mortality. We present a health economics model to understand the impact of using linezolid as the first-line treatment of MRSA NP in Taiwan. METHODS: We developed a cost-effectiveness model to estimate the costs and clinical outcomes of using linezolid 600 mg b.i.d. versus vancomycin 15 mg/kg b.i.d. as the first-line treatment of MRSA NP in Taiwan. The model is a decision-analytic analysis in which a MRSA-confirmed patient is simulated to utilize one of the treatments, using data from a clinical trial. Within each treatment arm, the patient can or cannot achieve clinical cure. Regardless of whether the clinical cure was achieved or not, the patient may or may not have experienced an adverse event. The per-protocol results for clinical cure were 57.6% and 46.6% for linezolid and vancomycin, respectively. RESULTS: The total cost of linezolid was $376 more per patient than that of vancomycin. Drug costs were higher for linezolid than for vancomycin ($1108 vs. $233), and hospitalization costs were lower ($4998 vs. $5496). With higher cost and higher cure rates for linezolid, the incremental cost per cure was $3421. CONCLUSION: This study projects linezolid to have higher drug costs, lower hospital costs, and higher overall costs compared with vancomycin. This is balanced against the higher clinical cure rate for linezolid. Depending on the willingness to pay for clinical cure, linezolid could be cost effective as the first-line treatment of NP in Taiwan.

The Lifetime Economic Burden of Inaccurate HER2 Testing: Estimating the Costs of False-Positive and False-Negative HER2 Test Results in US Patients with Early-Stage Breast Cancer.

BACKGROUND: Patients with breast cancer whose tumors test positive for human epidermal growth factor receptor 2 (HER2) are treated with HER2-targeted therapies such as trastuzumab, but limitations with HER2 testing may lead to false-positive (FP) or false-negative (FN) results. OBJECTIVES: To develop a US-level model to estimate the effect of tumor misclassification on health care costs and patient quality-adjusted life-years (QALYs). METHODS: Decision analysis was used to estimate the number of patients with early-stage breast cancer (EBC) whose HER2 status was misclassified in 2012. FP results were assumed to generate unnecessary trastuzumab costs and unnecessary cases of trastuzumab-related cardiotoxicity. FN results were assumed to save money on trastuzumab, but with a loss of QALYs and greater risk of disease recurrence and its associated costs. QALYs were valued at $100,000 under a net monetary benefit approach. RESULTS: Among 226,870 women diagnosed with EBC in 2012, 3.12% (n = 7,070) and 2.18% (n = 4,955) were estimated to have had FP and FN test results, respectively. Approximately 8400 QALYs (discounted, lifetime) were lost among women not receiving trastuzumab because of FN results. The estimated incremental per-patient lifetime burden of FP or FN results was $58,900 and $116,000, respectively. The implied incremental losses to society were $417 million and $575 million, respectively. CONCLUSIONS: HER2 tests result in misclassification and nonoptimal treatment of approximately 12,025 US patients with EBC annually. The total economic societal loss of nearly $1 billion suggests that improvements in HER2 testing accuracy are needed and that further clinical and economic studies are warranted.

Cost-effectiveness of bariatric surgical procedures for the treatment of severe obesity.

OBJECTIVE: One-third of Americans are obese and an increasing number opt for bariatric surgery. This study estimates the cost-effectiveness of common bariatric surgical procedures from a healthcare system perspective. METHODS: We evaluated the three most common bariatric surgical procedures in the US: laparoscopic gastric bypass (LRYGB), conventional (open) Roux-en-Y gastric bypass (ORYGB), and laparoscopic adjustable gastric banding (LAGB) compared to no surgery. The reference case was defined as a 53-year old female with body mass index (BMI) of 44 kg/m(2). We developed a two-part model using a deterministic approach for the first 5-year period post-surgery and separate empirical forecasts for the natural history of BMI, costs and outcomes in the remaining years. We used a combination of datasets including Medicare and MarketScan(®) together with estimates from the literature to populate the model. RESULTS: Bariatric surgery produced additional life expectancy (80-81 years) compared to no surgery (78 years). The incremental cost-effectiveness ratios (ICERs) of the surgical procedures were US $6,600 per quality-adjusted life expectancy (QALY) gained for LRYGB, US $6,200 for LAGB, and US $17,300 for ORYGB (3 % discount rate for cost and QALYs). ICERs varied according to choice of BMI forecasting method and clinically plausible variation in parameter estimates. In most scenarios, the ICER did not exceed a threshold of US $50,000 per QALY gained.

Modelling the long-term outcomes of bariatric surgery: A review of cost-effectiveness studies.

Obesity, defined as BMI ≥30 kg/m(2), affects over 30% of the United States adult population and has been declared an epidemic by the Centers for Disease Control. Bariatric surgery is a treatment option to reduce excess weight and is available to individuals with BMI greater than 40 kg/m(2), or 35 kg/m(2) with obesity-related comorbidities. As surgical options have become more common, researchers have analysed the long-term cost-effectiveness of these procedures. However, the follow-up data on patients is limited, and modelers need to forecast lifetime costs and outcomes for this chronic disease. In this chapter, we conduct a systematic literature review of cost-effectiveness studies on bariatric surgery to understand the forecasting methods used in practice. We identified six unique studies, which used statistical models, Markov models, or assumptions to forecast lifetime outcomes. We discuss each of the approaches, so clinicians, policy-makers, and payers can make informed interpretations based on the models.

BMI trajectories among the severely obese: results from an electronic medical record population.

Epidemiological studies have documented the growing prevalence of severe obesity during the past three decades. The primary goal of this study was to estimate the trajectory of BMI change over 5+ years in a cohort of subjects identified as severely obese (BMI ≥35). We conducted a retrospective cohort study among adults enrolled in Group Health (GH) in Washington State. We tracked 11,735 subjects with at least one BMI measure of 35 or greater in the calendar year 2005 through April 2010. Population averaged BMI trajectories were estimated as a quadratic function of time using a marginal regression model, adjusting for gender and baseline BMI and age. For the average male in GH, the estimated BMI trajectory exhibited a slightly inverted U-shaped pattern and a 0.17 increase in BMI over the sample period. For the average female, the BMI trajectory was slightly U-shaped with BMI decreasing 0.03 units over the sample period. We found a high degree of heterogeneity in the shape of estimated trajectories across baseline characteristics with larger 5-year BMI increases among younger subjects with a lower initial BMI. We conclude that BMI changes over 5 years among individuals classified as severely obese are generally small and consistent with studies documenting BMI changes for individuals in other lower BMI categories. Our results also suggest that once the 35 BMI threshold is reached, individuals will continue to remain severely obese, especially at younger ages.

Examining the BMI-mortality relationship using fractional polynomials.

BACKGROUND: Many previous studies estimating the relationship between body mass index (BMI) and mortality impose assumptions regarding the functional form for BMI and result in conflicting findings. This study investigated a flexible data driven modelling approach to determine the nonlinear and asymmetric functional form for BMI used to examine the relationship between mortality and obesity. This approach was then compared against other commonly used regression models. METHODS: This study used data from the National Health Interview Survey, between 1997 and 2000. Respondents were linked to the National Death Index with mortality follow-up through 2005. We estimated 5-year all-cause mortality for adults over age 18 using the logistic regression model adjusting for BMI, age and smoking status. All analyses were stratified by sex. The multivariable fractional polynomials (MFP) procedure was employed to determine the best fitting functional form for BMI and evaluated against the model that includes linear and quadratic terms for BMI and the model that groups BMI into standard weight status categories using a deviance difference test. Estimated BMI-mortality curves across models were then compared graphically. RESULTS: The best fitting adjustment model contained the powers -1 and -2 for BMI. The relationship between 5-year mortality and BMI when estimated using the MFP approach exhibited a J-shaped pattern for women and a U-shaped pattern for men. A deviance difference test showed a statistically significant improvement in model fit compared to other BMI functions. We found important differences between the MFP model and other commonly used models with regard to the shape and nadir of the BMI-mortality curve and mortality estimates. CONCLUSIONS: The MFP approach provides a robust alternative to categorization or conventional linear-quadratic models for BMI, which limit the number of curve shapes. The approach is potentially useful in estimating the relationship between the full spectrum of BMI values and other health outcomes, or costs.