Prediction of Overall Disease Burden in (y)pN1 Breast Cancer Using Knowledge-Based Machine Learning Model

BACKGROUND

We aimed to construct an expert knowledge-based Bayesian network (BN) model for assessing the overall disease burden (ODB) in (y)pN1 breast cancer patients and compare ODB across arms of ongoing trials.

METHODS

Utilizing institutional data and expert surveys, we developed a BN model for (y)pN1 breast cancer. Expert-derived probabilities and disability weights for radiotherapy-related benefit (e.g., 7-year disease-free survival [DFS]) and toxicities were integrated into the model. ODB was defined as the sum of disability weights multiplied by probabilities. In silico predictions were conducted for Alliance A011202, PORT-N1, RAPCHEM, and RT-CHARM trials, comparing ODB, 7-year DFS, and side effects.

RESULTS

In the Alliance A011202 trial, 7-year DFS was 80.1% in both arms. Axillary lymph node dissection led to higher clinical lymphedema and ODB compared to sentinel lymph node biopsy with full regional nodal irradiation (RNI). In the PORT-N1 trial, the control arm (whole-breast irradiation [WBI] with RNI or post-mastectomy radiotherapy [PMRT]) had an ODB of 0.254, while the experimental arm (WBI alone or no PMRT) had an ODB of 0.255. In the RAPCHEM trial, the radiotherapy field did not impact the 7-year DFS in ypN1 patients. However, there was a mild ODB increase with a larger irradiation field. In the RT-CHARM trial, we identified factors associated with the major complication rate, which ranged from 18.3% to 22.1%.

CONCLUSIONS

The expert knowledge-based BN model predicted ongoing trial outcomes, validating reported results and assumptions. In addition, the model demonstrated the ODB in different arms, with an emphasis on quality of life.

Burden of disease of spinal muscular atrophy linked to chromosome 5q (5q-SMA) in Colombia

OBJECTIVE

This article estimates the disease burden of 5q-SMA in Colombia by using the Disability-Adjusted Life Years (DALYs) metric.

METHODS

Epidemiological data were obtained from local databases and medical literature and were adjusted in the DisMod II tool. DALYs were obtained by adding years of life lost due to premature death (YLL) and years lived with disability (YLD).

RESULTS

The modeled prevalence of 5q-SMA in Colombia was 0.74 per 100,000 population. The fatality rate for all types was 14.1%. The disease burden of 5q-SMA was estimated at 4,421 DALYs (8.6 DALYs/100,000), corresponding to 4,214 (95.3%) YLLs and 207 (4.7%) YLDs. Most of the DALYs were accounted in the 2-17 age group. Of the total burden, 78% correspond to SMA type 1, 18% to type 2, and 4% to type 3.

CONCLUSIONS

Although 5q-SMA is a rare disease, it is linked to a significant disease burden due to premature mortality and severe sequelae. The estimates shown in this article are important inputs to inform public policy decisions on how to ensure adequate health service provision for patients with 5q-SMA.

Burn Patient Perspectives on Disability Weights and the Philosophy of Disability: A Gap in the Literature

Background

Disability-adjusted life years (DALY) have a ubiquitous presence in academic global health, including attempts to understand the global burden of burn injuries.

Objective

The present scoping review aimed to examine whether disability weights (DWs) were informed by burn patient perspectives and secondarily to determine whether literature indicates which of the three most common philosophical models of disability best aligns with burn patient experiences.

Methods

A review of six databases was conducted and The Critical Appraisal Skills Program (CASP) checklist was utilized.

Results

Out of a total of 764 articles, zero studies solicited patient perspectives of DWs. Four articles contained data that could be extrapolated to patient perspectives on disability. All articles utilized semi-structured interviews of burn survivors and reported thematic elements including return to work, self-image, and social integration. Patients reported similar themes that burn injuries were disabling injuries and instrumentally detrimental, with modulation based on the patient's social circumstances.

Conclusions

This scoping review highlights a significant gap in literature. First, no studies were found directly investigating burn patient perspectives on burn DWs. Current DWs have been derived from expert opinions with limited input from patients. Second, the limited primary patient data gleaned from this review suggest patients consider their injuries as instrumentally detrimental, which aligns most closely with the welfarist view of disability. More explicit investigations into the philosophical model of disability best aligning with burn patient experiences are needed to ground the health economics of burns in sound theory.

Understanding community perception and disability weights - A qualitative exploration of reasons associated with values in two states of India

Background

Health state valuation attempts to evaluate health states based on the perception of individuals. The values are used to derive disability weights (DWs) -an important metric for estimation of disability-adjusted life years and thereby calculation of the burden of diseases. Several studies have calculated DWs using different methods of valuation, however, very few have attempted to explore the underlying cause for assigning values to different health states. This study aims to document the perceptions, preferences, and social context in assigning DWs to given health states.

Methods

A total of 42 community members and 21 service providers (from public and private sectors) across urban and rural Odisha and Telangana were interviewed between July to September 2018. A face-to-face in-depth interview and a rank ordering technique through card sort exercise was employed to explore reasons and perceptions of individuals in the context of health states using the thematic framework approach.

Findings

Six themes emerged through analysis: awareness of the health state, nature of the disease, disease consequences, treatment-related issues, social implications, and case burden. Each theme captured an individual's reason for valuing one health state as different from the other, with differences and/or similarities between community members and service providers.

Conclusion

Our study provides a comprehensive comparison between contrasting groups of individuals, thereby suggesting mere acceptance of 'experts' reasoning may not always suffice. Further research studies in the future need to be conducted for a better insight into the health perspective of a culturally diverse community. It can also help estimate the burden of disease for decision making and resource allocation in developing countries.

Patients' Self-Reported Disability Weights of Top-Ranking Diseases in Thailand: Do They Differ by Socio-Demographic and Illness Characteristics?

Little is known about the impact of methodological decisions on estimating disability weights among patients with mental and physical disorders, and the effects of socio-demographic status on the estimation of these weights. A cross-sectional study was conducted in three hospitals in southern Thailand to describe the disability weights based on different valuation methods. Altogether, 150 patients with major depressive disorder, 150 with alcohol use disorder, and 150 with osteoarthritis with varying levels of severity were recruited. Using a face-to-face interview, all patients completed a visual analogue scale (VAS) and were randomly assigned to complete either the European Quality of Life-5 Dimensions (EQ-5D) or Time-trade-off (TTO) instrument to estimate their current utility score, which was consequently transformed to a disability weight. Significant differences were found between disability weights derived from the three instruments for the same disease, with the VAS providing the highest and EQ-5D the lowest weights. Patients with major depressive disorder had the highest disability weight while those with osteoarthritis had lowest by most methods. Patients’ socio-demographics do not affect how they perceive their disability or health condition. Our findings highlight the importance of carefully selecting methods of valuing disability weights, which can rely on disease specific conditions.

Describing the Development of a Health State Valuation Protocol to Obtain Community-Derived Disability Weights

For the prioritization of the allocation of national resources, estimating the burden of disease studies play a critical role. Hence the first Global Burden of Disease study conducted in the 1990s was done for this particular estimation. By the means of introducing disability-adjusted life year (DALY) metric, the burden of various diseases was calculated using disability weights (DWs)—a component of DALY. DWs are values that capture individuals' perception regarding the severity of diseases that involve valuation tools and health state descriptions. Various studies have been conducted over the past few decades to evaluate health states and derive disease-specific disability weights using Person-Trade off, Time-trade off, etc. However, use of these complex and cognitively demanding methods has been carried out in developed countries where the bulk of the populace is more educated. Few attempts have been made in low- and middle-income countries such as India, where not only the majority is less educated but also the social construction of diseases and health conditions are diverse. Therefore, due to the absence of methodological protocols of health state valuations for application at the community-level in the developing world, we attempted to systematically describe the procedure that can be used universally and cross-culturally for various health states. We began with the tentative selection of health states and health states valuation methods by conducting a meticulous literature review, followed by community exploration and medical consultations. This led to developing vignettes (clinical description) and 6D5L pictorial narrations (functional status description). Two field tests for checking the usability and refinement of the tools was done. Final consultation by an expert panel comprising of medical and non-medical professionals was held/conducted to finalize the health state labels and functional status profiles of each health state. The methodical approach provides a robust and thorough procedure for guiding researchers to implement health state valuation studies at community level.

Disability Weights for Chronic Mercury Intoxication Resulting from Gold Mining Activities: Results from an Online Pairwise Comparisons Survey

In artisanal small-scale gold mining, mercury is used for gold-extraction, putting miners and nearby residents at risk of chronic metallic mercury vapor intoxication (CMMVI). Burden of disease (BoD) analyses allow the estimation of the public health relevance of CMMVI, but until now there have been no specific CMMVI disability weights (DWs). The objective is to derive DWs for moderate and severe CMMVI. Disease-specific and generic health state descriptions of 18 diseases were used in a pairwise comparison survey. Mercury and BoD experts were invited to participate in an online survey. Data were analyzed using probit regression. Local regression was used to make the DWs comparable to the Global Burden of Disease (GBD) study. Alternative survey (visual analogue scale) and data analyses approaches (linear interpolation) were evaluated in scenario analyses. A total of 105 participants completed the questionnaire. DWs for moderate and severe CMMVI were 0.368 (0.261-0.484) and 0.588 (0.193-0.907), respectively. Scenario analyses resulted in higher mean values. The results are limited by the sample size, group of interviewees, questionnaire extent, and lack of generally accepted health state descriptions. DWs were derived to improve the data basis of mercury-related BoD estimates, providing useful information for policy-making. Integration of the results into the GBD DWs enhances comparability.

Disability weights from a household survey in a low socio-economic setting: how does it compare to the global burden of disease 2010 study?

Background

The global burden of disease (GBD) 2010 study used a universal set of disability weights to estimate disability adjusted life years (DALYs) by country. However, it is not clear whether these weights can be applied universally in calculating DALYs to inform local decision-making. This study derived disability weights for a resource-constrained community in Cape Town, South Africa, and interrogated whether the GBD 2010 disability weights necessarily represent the preferences of economically disadvantaged communities.

Design

A household survey was conducted in Lavender Hill, Cape Town, to assess the health state preferences of the general public. The responses from a paired comparison valuation method were assessed using a probit regression. The probit coefficients were anchored onto the 0 to 1 disability weight scale by running a lowess regression on the GBD 2010 disability weights and interpolating the coefficients between the upper and lower limit of the smoothed disability weights.

Results

Heroin and opioid dependence had the highest disability weight of 0.630, whereas intellectual disability had the lowest (0.040). Untreated injuries ranked higher than severe mental disorders. There were some counterintuitive results, such as moderate (15th) and severe vision impairment (16th) ranking higher than blindness (20th). A moderate correlation between the disability weights of the local study and those of the GBD 2010 study was observed (R²=0.440, p<0.05). This indicates that there was a relationship, although some conditions, such as untreated fracture of the radius or ulna, showed large variability in disability weights (0.488 in local study and 0.043 in GBD 2010).

Conclusions

Respondents seemed to value physical mobility higher than cognitive functioning, which is in contrast to the GBD 2010 study. This study shows that not all health state preferences are universal. Studies estimating DALYs need to derive local disability weights using methods that are less cognitively demanding for respondents.

The measurement of disability weights for 18 prevalent acute poisoning conditions

BACKGROUND

Disability weights (DWs) are used in disease burden studies, with the calculation of the weight of the disability as years lived with disability versus years of lost life accounting for mortalities. Currently, there is a single DW score available for poisoning, which is considered to be a single health state. This makes it difficult to evaluate the differing burdens of poisonings involving various substances/conditions in comparison with other health states in countries with different patterns of substance abuse. The aim of this study is therefore to estimate the DWs of 18 common poisonings based on the expert elicitation method.

METHODS

A panel of 10 medical clinicians who were familiar with the clinical aspects of different poisonings estimated the DWs of 50 health states by interpolating them on a calibrated Visual Analogue Scale. The DWs of some poisonings, such as alcohol, cannabis and heroin, had been estimated in previous studies and so were used to determine the external consistency of our panel. As a matter of routine, the DWs could vary on a scale between 0 (best health state) and 1 (worst health state).

RESULTS

Statistical analysis showed that both the internal (Cronbach's α = 0.912) and external consistency of the panel were acceptable. The DWs for the different poisonings were estimated along a range from 0.830 for severe aluminium phosphide to 0.022 for mild benzodiazepine.

CONCLUSIONS

Different poisonings should be weighted differently since they vary widely. Unfortunately, they are currently all weighted the same.

Disability-adjusted-life-years losses in postmenopausal women with osteoporosis: a burden of illness study

BACKGROUND

To estimate the disability-adjusted life years (DALY) in a nationwide representative sample of postmenopausal women with osteoporosis. The effects of drug-based therapy and risk factors for osteoporotic bone fractures on DALY losses were also explored.

METHODS

DALY were estimated based on participant's clinical characteristics and Health-Related Quality-of-Life (HRQoL) data obtained from a cross-sectional, epidemiological one-visit study (the GINERISK study). The study enrolled postmenopausal women (at least 12-months after their last menstrual period) with osteoporosis, above 18-years old, who attended Spanish outpatient Gynaecology clinics. HRQoL was assessed using the generic SF-12v2 questionnaire, which was used to derive disutility values. Mortality rates were extracted from the Spanish national statistics database. Factors explored to be associated with DALY losses were examined using ANOVA, ANCOVA and MANCOVA models.

RESULTS

DALY could be computed in 2,782 (67%) out of 4,157 postmenopausal women, with a mean (95% CI) age of 61.0 (60.7-61.2) years. Overall individual undiscounted DALY per woman were 6.1 (5.9-6.2), resulting to be significantly higher in women with severe osteoporosis with prior bone fracture; 7.8 (7.2-8.4) compared to osteoporotic women [5.8 (5.6-6.0)] or postmenopausal women with a BMD > -2.5 T-score that received a drug-based therapy [6.2 (5.8-6.5)]; F = 27.0 (P < 0.01). Models explaining the variation in the levels of health based on the use of a selective estrogen receptor modulator (SERM) or possession of risk factors for osteoporotic BF were found (P < 0.05).

CONCLUSIONS

DALY losses were considerable amongst postmenopausal women with osteoporosis. Not having a prior bone fracture, being older, using a SERM and having less osteoporotic risk factors were all linked to less DALY losses.

Establishing disability weights from pairwise comparisons for a US burden of disease study

To determine valid and reliable disability weights for a U.S. burden of disease study, a convenience sample of 68 clinical experts was recruited, including representatives from over 20 NIH institutes and Centers for Disease Control and Prevention. Experts were given various health state valuation tasks including pairwise comparison, ranking, and Person Trade Off. Materials consisted of standardized descriptions of 11 attributes per health state (Classification and Measurement System of Functional Health, CLAMES). Attributes comprised up to 5 ordinal levels of disability. All states were displayed either with or without health state labels. Health state descriptions were taken from an existing comprehensive Canadian system. Conditional Logistic (CLR) and Probit Regression (PR) were used to derive disability weights. CLR and PR converged in yielding stable regression weights to construct disability weights, with a correlation of 0.816. The overall test-retest reliability amounted to 92.5% identical decisions. No significant difference was found for the presentation of health states with or without labels. A comparison of the expert valuations from our study with a standard gamble based valuation in the general population resulted in agreement of r = 0.61. The chosen methodology yielded valid and reliable and disability weights. As it is based on a modularized set of attributes, this methodology will allow derivation of disability weights on the basis of existing descriptions using the CLAMES.