An overview of the use of the fracture risk assessment tool (FRAX) in osteoporosis.

FRAX®, a simple-to-use fracture risk calculator, was first released in 2008 and since then has been used increasingly worldwide. By calculating the 10-year probabilities of a major osteoporotic fracture and hip fracture, it assists clinicians when deciding whether further investigation, for example a bone mineral density measurement (BMD), and/or treatment is needed to prevent future fractures. In this review, we explore the literature around osteoporosis and how FRAX has changed its management. We present the characteristics of this tool and describe the use of thresholds (diagnostic and therapeutic). We also present arguments as to why screening with FRAX should be considered. FRAX has several limitations which are described in this review. This review coincides with the release of a version, FRAXplus, which addresses some of these limitations.

Previous fracture and subsequent fracture risk: a meta-analysis to update FRAX.

A large international meta-analysis using primary data from 64 cohorts has quantified the increased risk of fracture associated with a previous history of fracture for future use in FRAX. INTRODUCTION: The aim of this study was to quantify the fracture risk associated with a prior fracture on an international basis and to explore the relationship of this risk with age, sex, time since baseline and bone mineral density (BMD). METHODS: We studied 665,971 men and 1,438,535 women from 64 cohorts in 32 countries followed for a total of 19.5 million person-years. The effect of a prior history of fracture on the risk of any clinical fracture, any osteoporotic fracture, major osteoporotic fracture, and hip fracture alone was examined using an extended Poisson model in each cohort. Covariates examined were age, sex, BMD, and duration of follow-up. The results of the different studies were merged by using the weighted ß-coefficients. RESULTS: A previous fracture history, compared with individuals without a prior fracture, was associated with a significantly increased risk of any clinical fracture (hazard ratio, HR = 1.88; 95% CI = 1.72-2.07). The risk ratio was similar for the outcome of osteoporotic fracture (HR = 1.87; 95% CI = 1.69-2.07), major osteoporotic fracture (HR = 1.83; 95% CI = 1.63-2.06), or for hip fracture (HR = 1.82; 95% CI = 1.62-2.06). There was no significant difference in risk ratio between men and women. Subsequent fracture risk was marginally downward adjusted when account was taken of BMD. Low BMD explained a minority of the risk for any clinical fracture (14%), osteoporotic fracture (17%), and for hip fracture (33%). The risk ratio for all fracture outcomes related to prior fracture decreased significantly with adjustment for age and time since baseline examination. CONCLUSION: A previous history of fracture confers an increased risk of fracture of substantial importance beyond that explained by BMD. The effect is similar in men and women. Its quantitation on an international basis permits the more accurate use of this risk factor in case finding strategies.

Increased fracture risk in Parkinson's disease - An exploration of mechanisms and consequences for fracture prediction with FRAX.

The relative contributions of factors such as muscle strength, falls risk and low bone mineral density (BMD) to increased fracture risk in Parkinson's Disease (PD) were examined in an analysis of 5212 community-dwelling women age 75 years or more recruited to a randomised, double-blind, placebo-controlled study of the oral bisphosphonate, clodronate. Similar number of PD and non-PD subjects received treatment. Each participant had measurements of hip and forearm BMD, muscle strength (hand grip strength and maximum isometric quadriceps strength), ability in the sit-to-stand test, and postural stability. Incident radiographic and/or surgically verified fractures, and deaths, were recorded over an average follow-up of 3.8 years. A diagnosis of PD was made if it was self-reported and appropriate medication was recorded at the study entry. 47 of the women (0.9 %) had a diagnosis of PD at baseline. They were of similar age to those without PD, but reported higher disability scores and lower quality of life. While BMD at the forearm and hip regions was lower in PD, this only reached statistical significance at the femoral neck (0.61 ± 0.12 vs 0.65 ± 0.12 g/cm2, p = 0.037). Right hand grip strength was non-significantly lower in PD, but maximum right quadriceps strength was much reduced (96.9 ± 49.3 vs 126.3 ± 59.2 N, p = 0.003). Eleven (23.4 %) of the women with PD sustained 12 fractures, while 609 women (11.8 %) without PD sustained 742 osteoporotic fractures. The risk of osteoporotic fracture associated with PD was 2.24-fold higher in women with PD (Cox-regression HR 2.24, 95 % CI 1.23-4.06) and this remained high when adjusted for death as a competing risk (2.17, 95 % CI 1.17-4.01, p = 0.013). Following adjustment for femoral neck BMD, PD remained a significant predictor of fracture (HR 2.04, 1.12-3.70, p = 0.020). Entering PD as a risk variable using the rheumatoid arthritis input as a surrogate resulted in a reduction in PD as a FRAX-independent risk factor, particularly when BMD was included in FRAX (1.65, 95 % CI), but the relationship between PD and fracture risk appears to remain of clinical significance. The study suggests that PD may be an independent input in future iterations of FRAX, possibly due to non-skeletal components of risk such as reduced lower limb muscle strength. Introducing measures of muscle strength and performance in FRAX could also be considered.

Is it time to consider population screening for fracture risk in postmenopausal women? A position paper from the International Osteoporosis Foundation Epidemiology/Quality of Life Working Group.

The IOF Epidemiology and Quality of Life Working Group has reviewed the potential role of population screening for high hip fracture risk against well-established criteria. The report concludes that such an approach should strongly be considered in many health care systems to reduce the burden of hip fractures. INTRODUCTION: The burden of long-term osteoporosis management falls on primary care in most healthcare systems. However, a wide and stable treatment gap exists in many such settings; most of which appears to be secondary to a lack of awareness of fracture risk. Screening is a public health measure for the purpose of identifying individuals who are likely to benefit from further investigations and/or treatment to reduce the risk of a disease or its complications. The purpose of this report was to review the evidence for a potential screening programme to identify postmenopausal women at increased risk of hip fracture. METHODS: The approach took well-established criteria for the development of a screening program, adapted by the UK National Screening Committee, and sought the opinion of 20 members of the International Osteoporosis Foundation's Working Group on Epidemiology and Quality of Life as to whether each criterion was met (yes, partial or no). For each criterion, the evidence base was then reviewed and summarized. RESULTS AND CONCLUSION: The report concludes that evidence supports the proposal that screening for high fracture risk in primary care should strongly be considered for incorporation into many health care systems to reduce the burden of fractures, particularly hip fractures. The key remaining hurdles to overcome are engagement with primary care healthcare professionals, and the implementation of systems that facilitate and maintain the screening program.

Update of the fracture risk prediction tool FRAX: a systematic review of potential cohorts and analysis plan.

We describe the collection of cohorts together with the analysis plan for an update of the fracture risk prediction tool FRAX with respect to current and novel risk factors. The resource comprises 2,138,428 participants with a follow-up of approximately 20 million person-years and 116,117 documented incident major osteoporotic fractures. INTRODUCTION: The availability of the fracture risk assessment tool FRAX® has substantially enhanced the targeting of treatment to those at high risk of fracture with FRAX now incorporated into more than 100 clinical osteoporosis guidelines worldwide. The aim of this study is to determine whether the current algorithms can be further optimised with respect to current and novel risk factors. METHODS: A computerised literature search was performed in PubMed from inception until May 17, 2019, to identify eligible cohorts for updating the FRAX coefficients. Additionally, we searched the abstracts of conference proceedings of the American Society for Bone and Mineral Research, European Calcified Tissue Society and World Congress of Osteoporosis. Prospective cohort studies with data on baseline clinical risk factors and incident fractures were eligible. RESULTS: Of the 836 records retrieved, 53 were selected for full-text assessment after screening on title and abstract. Twelve cohorts were deemed eligible and of these, 4 novel cohorts were identified. These cohorts, together with 60 previously identified cohorts, will provide the resource for constructing an updated version of FRAX comprising 2,138,428 participants with a follow-up of approximately 20 million person-years and 116,117 documented incident major osteoporotic fractures. For each known and candidate risk factor, multivariate hazard functions for hip fracture, major osteoporotic fracture and death will be tested using extended Poisson regression. Sex- and/or ethnicity-specific differences in the weights of the risk factors will be investigated. After meta-analyses of the cohort-specific beta coefficients for each risk factor, models comprising 10-year probability of hip and major osteoporotic fracture, with or without femoral neck bone mineral density, will be computed. CONCLUSIONS: These assembled cohorts and described models will provide the framework for an updated FRAX tool enabling enhanced assessment of fracture risk (PROSPERO (CRD42021227266)).

FRAX-based intervention thresholds for Pakistan.

We compared, for women in Pakistan, the utility of intervention thresholds either at a T-score ≤ - 2.5 or based on a FRAX probability equivalent to women of average body mass index (BMI) with a prior fragility fracture. Whereas the FRAX-based intervention threshold identified women at high fracture probability, the T-score threshold was less sensitive, and the associated fracture risk decreased markedly with age. PURPOSE: The fracture risk assessment algorithm FRAX® has been recently calibrated for Pakistan, but guidance is needed on how to apply fracture probabilities to clinical practice. METHODS: The age-specific 10-year probabilities of a major osteoporotic fracture were calculated in women with average BMI to determine fracture probabilities at two potential intervention thresholds. The first comprised the age-specific fracture probabilities associated with a femoral neck T-score of - 2.5. The second approach determined age-specific fracture probabilities that were equivalent to a woman with a prior fragility fracture, without bone mineral density (BMD). The parsimonious use of BMD was additionally explored by the computation of upper and lower assessment thresholds for BMD testing. RESULTS: When a BMD T-score ≤ - 2.5 was used as an intervention threshold, FRAX probabilities in women aged 50 years were approximately two-fold higher than in women of the same age but with no risk factors and average BMD. The relative increase in risk associated with the BMD threshold decreased progressively with age such that, at the age of 80 years or more, a T-score of - 2.5 was actually protective. The 10-year probability of a major osteoporotic fracture by age, equivalent to women with a previous fracture, rose with age from 2.1% at the age of 40 years to 17%, at the age of 90 years, and identified women at increased risk at all ages. CONCLUSION: Intervention thresholds based on BMD alone do not effectively target women at high fracture risk, particularly in the elderly. In contrast, intervention thresholds based on fracture probabilities equivalent to a 'fracture threshold' target women at high fracture risk.

Osteoporosis and fractures in women: the burden of disease.

Osteoporosis is a disease characterized by impaired bone microarchitecture and reduced bone mineral density (BMD) resulting in bone fragility and increased risk of fracture. In western societies, one in three women and one in five men will sustain an osteoporotic fracture in their remaining lifetime from the age of 50 years. Fragility fractures, especially of the spine and hip, commonly give rise to increased morbidity and mortality. In the five largest European countries and Sweden, fragility fractures were the cause of 2.6 million disability-adjusted life years in 2016 and the fracture-related costs increased from €29.6 billion in 2010 to €37.5 billion in 2017. In the European Union and the USA, only a small proportion of women eligible for pharmacological treatment are being prescribed osteoporosis medication. Secondary fracture prevention, using Fracture Liaison Services, can be used to increase the rates of fracture risk assessment, BMD testing and use of osteoporosis medication in order to reduce fracture numbers. Additionally, established primary prevention strategies, based on case-finding methods utilizing fracture prediction tools, such as FRAX, to identify women without fracture but with elevated risk, are recommended in order to further reduce fracture numbers.

Fracture risk assessment by the FRAX model.

The introduction of the FRAX algorithms has facilitated the assessment of fracture risk on the basis of fracture probability. FRAX integrates the influence of several well-validated risk factors for fracture with or without the use of bone mineral density. Since age-specific rates of fracture and death differ across the world, FRAX models are calibrated with regard to the epidemiology of hip fracture (preferably from national sources) and mortality (usually United Nations sources). Models are currently available for 73 nations or territories covering more than 80% of the world population. FRAX has been incorporated into more than 80 guidelines worldwide, although the nature of this application has been heterogeneous. The limitations of FRAX have been extensively reviewed. Arithmetic procedures have been proposed in order to address some of these limitations, which can be applied to conventional FRAX estimates to accommodate knowledge of dose exposure to glucocorticoids, concurrent data on lumbar spine bone mineral density, information on trabecular bone score, hip axis length, falls history, type 2 diabetes, immigration status and recency of prior fracture.

A country-specific FRAX model for Botswana.

INTRODUCTION: Hip fracture rates in Botswana were used to create a FRAX® model for fracture risk assessment. OBJECTIVE: This paper describes the development and characteristics of a country-specific FRAX model for Botswana. METHODS: Age-specific and sex-specific incidence of hip fracture and national mortality rates was incorporated into a FRAX model for Botswana. Ten-year fracture probabilities were compared with those from African countries having a FRAX model and African Americans from the USA. RESULTS: The probabilities of hip fracture and major osteoporotic fracture were low compared with those from South Africa (Black and Coloured) and US Blacks. Probabilities were marginally higher than for Tunisia. CONCLUSION: The creation of a FRAX model is expected to help guide decisions about the prevention and treatment of fragility fractures in Botswana.

An assessment of intervention thresholds for very high fracture risk applied to the NOGG guidelines : A report for the National Osteoporosis Guideline Group (NOGG).

The National Osteoporosis Guideline Group (NOGG) has developed intervention thresholds based on FRAX® to characterise patients at high and very high risk of fracture. INTRODUCTION: Guidelines for the assessment of fracture risk have begun to categorise patients eligible for treatment into high and very high risk of fracture to inform choice of therapeutic approach. The aim of the present study was to develop intervention thresholds based on the hybrid assessment model of NOGG. METHODS: We examined the impact of intervention thresholds in a simulated cross-sectional cohort of women age 50 years or more from the UK with the distribution of baseline characteristics based on that in the FRAX cohorts. The prevalence of very high risk using the hybrid model was compared with age-dependent thresholds used by the International Osteoporosis Foundation and the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (IOF/ESCEO). The appropriateness of thresholds was tested based on the populations treated with anabolic agents. RESULTS: With an upper intervention threshold using the IOF/ESCEO criteria, 56% of women age 50 years or more would be characterised at very high risk. This compares with 36% using the IOF/ESCEO criteria and an age-specific intervention threshold over all ages. With an upper intervention threshold of 1.6 times the pre-existing intervention threshold, 10% of women age 50 years or more would be characterised at very high risk. The data from phase 3 studies indicate that most trial participants exposed to romosozumab or teriparatide would fall into the very high-risk category. CONCLUSIONS: Proposals for FRAX-based criteria for very high risk for the NOGG hybrid model categorise a small proportion of women age 50 years or more (10%) in this highest risk stratum. The level of risk identified was comparable to that of women enrolled in trials of anabolic agents.

A surrogate FRAX model for Pakistan.

A surrogate FRAX® model for Pakistan has been constructed using age-specific hip fracture rates for Indians living in Singapore and age-specific mortality rates from Pakistan. INTRODUCTION: FRAX models are frequently requested for countries with little or no data on the incidence of hip fracture. In such circumstances, the International Society for Clinical Densitometry and International Osteoporosis Foundation have recommended the development of a surrogate FRAX model, based on country-specific mortality data but using fracture data from a country, usually within the region, where fracture rates are considered to be representative of the index country. OBJECTIVE: This paper describes the development and characteristics of a surrogate FRAX model for Pakistan. METHODS: The FRAX model used the ethnic-specific incidence of hip fracture in Indian men and women living in Singapore, combined with the death risk for Pakistan. RESULTS: The surrogate model gave somewhat lower 10-year fracture probabilities for men and women at all ages compared to the model for Indians from Singapore, reflecting a higher mortality risk in Pakistan. There were very close correlations in fracture probabilities between the surrogate and authentic models (r ≥ 0.998) so that the use of the Pakistan model had little impact on the rank order of risk. It was estimated that 36,524 hip fractures arose in 2015 in individuals over the age of 50 years in Pakistan, with a predicted increase by 214% to 114,820 in 2050. CONCLUSION: The surrogate FRAX model for Pakistan provides an opportunity to determine fracture probability within the Pakistan population and help guide decisions about treatment.

The effect on subsequent fracture risk of age, sex, and prior fracture site by recency of prior fracture.

The risk of a recurrent fragility fracture varies by age and sex, as by site and recency of sentinel fracture. INTRODUCTION: The recency of prior fractures affects subsequent fracture risk. Variable recency may obscure other factors that affect subsequent fracture risk. The aim of this study was to quantify the effect of a sentinel fracture by site, age, and sex where the recency was held constant. METHODS: The study used data from the Reykjavik Study fracture register that documented prospectively all fractures at all skeletal sites in a large sample of the population of Iceland. Fracture incidence was compared to that of the general population determined at fixed times after a sentinel fracture (humeral, clinical vertebral, forearm, hip, and minor fractures). Outcome fractures comprised a major osteoporotic fracture and hip fracture. RESULTS: Sentinel osteoporotic fractures were identified in 9504 men and women. Of these, 3616 individuals sustained a major osteoporotic fracture as the first subsequent fracture, of whom 1799 sustained a hip fracture. Hazard ratios for prior fracture were consistently higher in men than in women and decreased progressively with age. Hazard ratios varied according to the site of sentinel fracture with higher ratios for hip and vertebral fracture than for humerus, forearm, or minor osteoporotic fracture. CONCLUSION: The risk of a recurrent fragility fracture varies by age, sex, and site of sentinel fracture when recency is held constant.

Romosozumab efficacy on fracture outcomes is greater in patients at high baseline fracture risk: a post hoc analysis of the first year of the frame study.

This study aimed to determine the interaction between baseline FRAX® fracture probability and romosozumab efficacy. Using an ITT approach, it was determined that the efficacy of romosozumab on clinical fracture, osteoporotic fracture, and major osteoporotic fracture is significantly greater in patients at high baseline fracture risk, when compared with placebo. INTRODUCTION: Post hoc analyses of placebo-controlled osteoporosis treatment studies have shown significantly greater reductions of fracture incidence for higher fracture risk patients. This study determined the interaction between baseline FRAX® fracture probability and romosozumab efficacy in the placebo-controlled first year of the phase 3 FRAME study (NCT01575834). METHODS: Using an ITT approach, an extension of Poisson regression analysis studied the relationship between treatment, FRAX® 10-year probability of major osteoporotic fracture (MOF, calculated without BMD) and risk of first incident fracture (adjusting for age and follow-up time). Treatment interactions considered outcomes of all clinical fractures, osteoporotic fractures, MOF, clinical vertebral fractures, and morphometric vertebral fractures. Two-sided p value of < 0.1 for the interaction between treatment and FRAX® was considered significant. RESULTS: Compared with placebo, romosozumab reduced the incidence of all fracture outcomes in the first year (range: 32% reduction in MOF [p = 0.07] to 80% reduction in clinical vertebral fractures [p = 0.038]). Significant interactions were observed between efficacy and baseline FRAX® probability for composite outcomes of clinical fractures, osteoporotic fractures, and MOF (p = 0.064-0.084), but not vertebral fractures (p > 0.3). For example, romosozumab decreased all clinical fractures by 22% at the 25th centile of FRAX® probability but the reduction was 41% at the 75th centile. Exclusion of vertebral fractures from each composite fracture outcome (i.e. only nonvertebral fractures included) showed even stronger interactions with baseline FRAX® probability (p = 0.036-0.046). CONCLUSIONS: Efficacy of romosozumab on clinical fracture, osteoporotic fracture, and MOF is significantly greater in patients at high baseline fracture risk compared with placebo.

Epidemiology of hip fracture in Botswana.

A retrospective population-based survey in the Republic of Botswana determined the incidence of fractures at the hip over 3 years. The estimated number of such fractures nationwide for 2020 was 103 and is predicted to increase. OBJECTIVE: This article describes the epidemiology of hip fractures in the Republic of Botswana. METHODS: A retrospective patient chart review was conducted to identify from hospital registers the number of patients diagnosed with hip fracture in 2009, 2010, and 2011. Age- and sex-specific incidence of hip fracture was determined from which lifetime probabilities and future projections for hip fracture were calculated. RESULTS: The incidence of hip fracture was low and comparable to rates reported from Tunisia. The remaining lifetime risk of hip fracture at the age of 50 years in men and women was 1.4 and 1.1%, respectively. The incidence of hip fracture suggested that the estimated number of hip fractures nationwide in persons over the age of 50 years for 2020 was 103 and is predicted to increase by more than threefold to 372 in 2050. CONCLUSION: The hip fracture rates can be used for healthcare planning. Additionally, these data can be used to create a FRAX model to help guide decisions about treatment.

The use of 2-, 5-, and 10-year probabilities to characterize fracture risk after a recent sentinel fracture.

The increase in fracture risk associated with a recent fragility fracture is more appropriately captured using a 10-year fracture probability than 2- or 5-year probabilities. INTRODUCTION: The recency of prior fractures affects subsequent fracture risk. The aim of this study was to quantify the effect of a recent sentinel fracture, by site, on the 2-, 5-, and 10-year probability of fracture. METHODS: The study used data from the Reykjavik Study fracture register that documented prospectively all fractures at all skeletal sites in a large sample of the population of Iceland. Fracture probabilities were determined after a sentinel fracture (humeral, clinical vertebral, forearm and hip fracture) occurring within the previous 2 years and probabilities for a prior osteoporotic fracture irrespective of recency. The probability ratios were used to adjust fracture probabilities over a 2-, 5-, and 10-year time horizon. RESULTS: As expected, probabilities decreased with decreasing time horizon. Probability ratios varied according to age and the site of sentinel fracture. Probability ratios to adjust for a prior fracture within the previous 2 years were higher the shorter the time horizon, but the absolute increases in fracture probabilities were much reduced. Thus, fracture probabilities were substantially lower with time horizons less than 10 years. CONCLUSION: The 10-year probability of fractures is the appropriate metric to capture the impact of the recency of sentinel fractures. The probability ratios provide adjustments to conventional FRAX estimates of fracture probability for recent sentinel fractures, adjustments which can readily inform clinical decision-making.

Global impact of COVID-19 on non-communicable disease management: descriptive analysis of access to FRAX fracture risk online tool for prevention of osteoporotic fractures.

The COVID-19 pandemic, and its management, is markedly impacting the management of osteoporosis as judged by access to online FRAX fracture risk assessments. Globally, access was 58% lower in April than in February 2020. Strategies to improve osteoporosis care, with greater use of fracture risk assessments, offer a partial solution. INTRODUCTION: The COVID-19 pandemic is having a significant detrimental impact on the management of chronic diseases including osteoporosis. We have quantified the global impact by examining changes in the usage of online FRAX fracture risk assessments before and after the declaration of the pandemic (11 March 2020). METHODS: The study comprised a retrospective analysis using GoogleAnalytics data on daily sessions on the FRAX® website ( www.sheffield.ac.uk/FRAX ) from November 2019 to April 2020 (main analysis period February-April 2020), and the geographical source of that activity. RESULTS: Over February-April 2020, the FRAX website recorded 460,495 sessions from 184 countries, with 210,656 sessions in February alone. In March and April, the number of sessions fell by 23.1% and 58.3% respectively, a pattern not observed over the same period in 2019. There were smaller reductions in Asia than elsewhere, partly related to earlier and less-marked nadirs in some countries (China, Taiwan, Hong Kong, South Korea and Vietnam). In Europe, the majority of countries (24/31, 77.4%) reduced usage by at least 50% in April. Seven countries showed smaller reductions (range - 2.85 to - 44.1%) including Poland, Slovakia, Czech Republic, Germany, Norway, Sweden and Finland. There was no significant relationship between the reduction in FRAX usage and measures of disease burden such as COVID-attributed deaths per million of the population. CONCLUSION: This study documents a marked global impact of the COVID-19 pandemic on the management of osteoporosis as reflected by FRAX online fracture risk assessments. The analysis suggests that impact may relate to the societal and healthcare measures taken to ameliorate the pandemic.

Combining fracture outcomes in phase 3 trials of osteoporosis: an analysis of the effects of denosumab in postmenopausal women.

This paper explores use of metrics that combine fracture outcomes that add power to phase 3 studies and provide a surrogate outcome for regulatory agencies. INTRODUCTION: The aim of this study was to develop an analytic framework that would combine information from all fracture outcomes (including radiographic vertebral fractures) in phase 3 studies to provide a metric for the assessment of treatment efficacy. METHODS: Data from the phase 3 study of denosumab were used as an exemplar comparing the effects of active intervention with placebo on the risk of all fractures associated with osteoporosis. Fracture outcomes were assigned utility weights drawn from the published literature and applied to age-specific health state values of the general population. For each fracture outcome in each arm of the study, cumulative disutility was computed to serve as the principal end point. The hypothesis tested was that treatment with denosumab results in a significant reduction in mean fracture-related disutility. RESULTS: Treatment with denosumab was associated with significantly lower utility loss compared with placebo. For patients treated with denosumab, mean utility loss was 42% less than with placebo (4.5 vs. 7.5 QALYs/1000 patient years, respectively, p < 0.001). CONCLUSIONS: Denosumab significantly decreased utility loss. The use of metrics that combine fracture outcomes may provide added power to phase 3 studies and provide a surrogate outcome for regulatory agencies.