Logical Inconsistencies in the Health Years in Total and Equal Value of Life-Years Gained.

OBJECTIVES: This study aimed to assess whether recently proposed alternatives to the quality-adjusted life-year (QALY), intended to address concerns about discrimination, are suitable for informing resource allocation decisions. METHODS: We consider 2 alternatives to the QALY: the health years in total (HYT), recently proposed by Basu et al, and the equal value of life-years gained (evLYG), currently used by the Institute for Clinical and Economic Review. For completeness we also consider unweighted life-years (LYs). Using a hypothetical example comparing 3 mutually exclusive treatment options, we consider how calculations are performed under each approach and whether the resulting rankings are logically consistent. We also explore some further challenges that arise from the unique properties of the HYT approach. RESULTS: The HYT and evLYG approaches can result in logical inconsistencies that do not arise under the QALY or LY approaches. HYT can violate the independence of irrelevant alternatives axiom, whereas the evLYG can produce an unstable ranking of treatment options. HYT have additional issues, including an implausible assumption that the utilities associated with health-related quality of life and LYs are "separable," and a consideration of "counterfactual" health-related quality of life for patients who are dead. CONCLUSIONS: The HYT and evLYG approaches can result in logically inconsistent decisions. We recommend that decision makers avoid these approaches and that the logical consistency of any approaches proposed in future be thoroughly explored before considering their use in practice.

Length of Stay and Home Discharge for Patients with Inpatient Stroke Rehabilitation.

OBJECTIVE: To examine temporal trends and geographic variations and predict inpatient rehabilitation (IPR) length of stay (LOS) and home discharge for stroke patients. METHODS: Patients aged ≥18 years who were admitted to an IPR facility in Alberta, Canada, between 04/2014 and 03/2018 (years 2014-2017) were included. Predictors of LOS and home discharge were examined using 2014-2016 data and validated using 2017 data. Multivariable linear regression (MLR), multivariable negative binomial (MNB), and multivariable quantile regressions (MQR) were used to examine LOS, and logistic regression was used for home discharge. RESULTS: We included 2686 rehabilitation admissions between 2014 and 2017. The mean LOS decreased (2014: 71 days; 2017: 62.1 days; p = 0.003) during the study period and was shortest in Edmonton (59.1 days) compared to Calgary (66 days) or other localities (70.8 days; p < 0.001). Three-quarters of patients were discharged home and this proportion remained unchanged between 2014 and 2017. Calgary patients were more likely to be discharged home than those in Edmonton (OR = 0.62; p = 0.019) or other localities (OR = 0.39; p = 0.011). The MLR and MNB models provided accurate prediction for the mean LOS (predicted = 59.9 and 60.8 days, respectively, vs. actual = 62.1 days; both p > 0.5), while the MQR model did so for the median LOS (predicted = 44.3 days vs. actual = 44 days; p = 0.09). The logistic regression resulted in 82.4% of correct prediction, a sensitivity of 91.6%, and a specificity of 50.7% for home discharge. CONCLUSIONS: Rehabilitation LOS decreased while the proportion of home discharge remained unchanged during the study period. Both varied across health zones. Identifiable statistical models provided accurate prediction with a separate patient cohort.

A systematic review of the accessibility, acceptability, safety, efficiency, clinical effectiveness, and cost-effectiveness of private cataract and orthopedic surgery clinics.

OBJECTIVES: Many publicly funded health systems use a mix of privately and publicly operated providers of care to deliver elective surgical services. The aim of this systematic review was to assess the role of privately operated but publicly funded provision of surgical services for adult patients who had cataract or orthopedic surgery within publicly funded health systems in high-income countries. METHODS: Electronic databases (Ovid MEDLINE, OVID Embase, and EBSCO EconLit) were searched on 26 March 2021, and gray literature sources were searched on 6 April 2021. Two reviewers independently applied inclusion and exclusion criteria to identify studies, and extracted data. The outcomes evaluated include accessibility, acceptability, safety, clinical effectiveness, efficiency, and cost/cost-effectiveness. RESULTS: Twenty-nine primary studies met the inclusion criteria and were synthesized narratively. We found mixed results across each of our reported outcomes. Wait times were shorter for patients treated in private facilities. There was evidence that some private facilities cherry-pick or cream-skim by selecting less complex patients, which increases the postoperative length of stay and costs for public facilities, restricts access to private facilities for certain groups of patients, and increases inequality within the health system. Seven studies found improved safety outcomes in private facilities, noting that private patients had a lower preoperative risk of complications. Only two studies reported cost and cost-effectiveness outcomes. One costing study concluded that private facilities' costs were lower than those of public facilities, and a cost-utility study showed that private contracting to reduce public waiting times for joint replacement was cost-effective. CONCLUSIONS: Limited evidence exists that private-sector contracts address existing healthcare delivery problems. Value for money also remains to be evaluated properly.

A Conceptual Framework for Life-Cycle Health Technology Assessment.

OBJECTIVES: Health technology assessment (HTA) uses evidence appraisal and synthesis with economic evaluation to inform adoption decisions. Standard HTA processes sometimes struggle to (1) support decisions that involve significant uncertainty and (2) encourage continued generation of and adaptation to new evidence. We propose the life-cycle (LC)-HTA framework, addressing these challenges by providing additional tools to decision makers and improving outcomes for all stakeholders. METHODS: Under the LC-HTA framework, HTA processes align to LC management. LC-HTA introduces changes in HTA methods to minimize analytic time while optimizing decision certainty. Where decision uncertainty exists, we recommend risk-based pricing and research-oriented managed access (ROMA). Contractual procurement agreements define the terms of reassessment and provide additional decision options to HTA agencies. LC-HTA extends value-of-information methods to inform ROMA agreements, leveraging routine, administrative data, and registries to reduce uncertainty. RESULTS: LC-HTA enables the adoption of high-value high-risk innovations while improving health system sustainability through risk-sharing and reducing uncertainty. Responsiveness to evolving evidence is improved through contractually embedded decision rules to simplify reassessment. ROMA allows conditional adoption to obtain additional information, with confidence that the net value of that adoption decision is positive. CONCLUSIONS: The LC-HTA framework improves outcomes for patients, sponsors, and payers. Patients benefit through earlier access to new technologies. Payers increase the value of the technologies they invest in and gain mechanisms to review investments. Sponsors benefit through greater certainty in outcomes related to their investment, swifter access to markets, and greater opportunities to demonstrate value.

An observational cohort study of health outcomes and costs associated with early pregnancy assessment units in the UK.

BACKGROUND: The objective of this study was to assess the impact of consultant presence, volume of patients seen and weekend opening on the health and cost-related outcomes associated with different Early Pregnancy Assessment Unit (EPAU) configurations. METHODS: This was an observational study with a prospective cohort design. Six thousand six hundred six pregnant women (16 years of age and over) attending EPAUs because of suspected early pregnancy complications were recruited from 44 EPAUs across the UK. The main outcome measures were quality of life, costs, and anxiety. RESULTS: Costs, quality of life and anxiety scores were similar across configurations with little evidence to suggest an impact of consultant presence, weekend opening or volume of patients seen. Mean overall costs varied from £92 (95% CI £85 - £98) for a diagnosis of normally developing pregnancy to £1793 (95% CI £1346 - £2240) for a molar pregnancy. EQ-5D-5L score increased from 0.85 (95% CI 0.84-0.86) at baseline to 0.91 (95% CI 0.90-0.92) at 4 weeks for the 573 women who completed questionnaires at both time points, largely due to improvements in the pain/discomfort and anxiety/depression dimensions. 78% of women reported a decrease in their anxiety score immediately following their EPAU appointment. CONCLUSIONS: EPAU configuration, as specified in this study, had limited impact on any of the outcomes examined. However, it is clear that care provided in the EPAU has a positive overall effect on women's health and emotional wellbeing, with significant improvements in EQ-5D and anxiety shown following an EPAU visit.

Interpersonal counselling versus perinatal-specific cognitive behavioural therapy for women with depression during pregnancy offered in routine psychological treatment services: a phase II randomised trial.

BACKGROUND: Up to one in eight women experience depression during pregnancy. In the UK, low intensity cognitive behavioural therapy (CBT) is the main psychological treatment offered for those with mild or moderate depression and is recommended during the perinatal period, however referral by midwives and take up of treatment by pregnant women is extremely low. Interpersonal Counselling (IPC) is a brief, low-intensity form of Interpersonal Psychotherapy (IPT) that focuses on areas of concern to service users during pregnancy. To improve psychological treatment for depression during pregnancy, the study aimed to assess the feasibility and acceptability of a trial of IPC for antenatal depression in routine NHS services compared to low intensity perinatal specific CBT. METHODS: We conducted a small randomised controlled trial in two centres. A total of 52 pregnant women with mild or moderate depression were randomised to receive 6 sessions of IPC or perinatal specific CBT. Treatment was provided by 12 junior mental health workers (jMHW). The primary outcome was the number of women recruited to the point of randomisation. Secondary outcomes included maternal mood, couple functioning, attachment, functioning, treatment adherence, and participant and staff acceptability. RESULTS: The study was feasible and acceptable. Recruitment was successful through scanning clinics, only 6 of the 52 women were recruited through midwives. 71% of women in IPC completed treatment. Women reported IPC was acceptable, and supervisors reported high treatment competence in IPC arm by jMHWs. Outcome measures indicated there was improvement in mood in both groups (Change in EPDS score IPC 4.4 (s.d. 5.1) and CBT 4.0 (s.d. 4.8). CONCLUSIONS: This was a feasibility study and was not large enough to detect important differences between IPC and perinatal specific CBT. A full-scale trial of IPC for antenatal depression in routine IAPT services is feasible. TRIAL REGISTRATION: This study has been registered with ISRCTN registry 11513120 . - date of registration 05/04/2018.

Caring for Carers: Positive and Normative Challenges for Future Research on Carer Spillover Effects in Economic Evaluation.

BACKGROUND: Many individuals rely on family and friends to provide care outside of the formal healthcare sector. The need for caring is driven by many factors, including government policies toward health and social care, and increased prevalence of chronic and comorbid conditions. Informal care may give rise to "spillover" effects from the health of a cared-for individual to the health of carers. Spillover effects are rarely reflected in economic evaluations, in spite of growing research interest in this area, and recommendations from bodies such as the National Institute for Health and Care Excellence (NICE) and the Second Panel on Cost-Effectiveness that effects of this type be included in cost-effectiveness analysis. OBJECTIVE: We explore the positive and normative issues to which the inclusion of carer spillover effects in economic evaluation may give rise and how future research might begin to address these challenges. RESULTS: Positive challenges include the identification of causal rather than coincidental impacts on carers, selection into caring, and the measurement and treatment of spillover effects. The normative issues are related to these challenges, and particularly include impacts on equity, and spillovers that improve rather than reduce the health of carers. CONCLUSIONS: We argue that challenges including spillover effects in economic evaluation are considerable. Avenues for future research and possible solutions to these challenges include a re-orientation of analytic perspectives so that the impacts of caring on carers are accounted for where appropriate, and the design of studies to collect robust evidence to inform debate and guidance development in this area.

Hard choices: Reflections from the tomb of the unknown patient.

Health Technology Assessment (HTA) has always sought to incorporate the evidence of all patients affected in the decision-making process. While health system budgets could increase to cover costs of new technologies, the relevant patients are those benefitting from access to the technology being appraised. More recently, with health system budgets effectively fixed, costs of new technologies are covered by displacing other, currently funded care. This reallocation means the patients affected by the decision include those whose healthcare is displaced. These patients are typically unidentified, however, and so HTA in this instance involves choosing between identified and unidentified patients. We argue that HTA should take account of identifiability bias in this decision-making, to avoid promoting inequitable and inefficient access to healthcare.

Addressing the double-burden of diabetes and tuberculosis: lessons from Kyrgyzstan.

BACKGROUND: The incidence of diabetes and tuberculosis co-morbidity is rising, yet little work has been done to understand potential implications for health systems, healthcare providers and individuals. Kyrgyzstan is a priority country for tuberculosis control and has a 5% prevalence of diabetes in adults, with many health system challenges for both conditions. METHODS: Patient exit interviews collected data on demographic and socio-economic characteristics, health spending and care seeking for people with diabetes, tuberculosis and both diabetes and tuberculosis. Qualitative data were collected through semi-structured interviews with healthcare workers involved in diabetes and tuberculosis care, to understand delivery of care and how providers view effectiveness of care. RESULTS: The experience of co-affected individuals within the health system is different than those just with tuberculosis or diabetes. Co-affected patients do not receive more care and also have different care for their tuberculosis than people with only tuberculosis. Very high levels of catastrophic spending are found among all groups despite these two conditions being included in the Kyrgyz state benefit package especially for medicines. CONCLUSIONS: This study highlights that different patterns of service provision by disease group are found. Although Kyrgyzstan has often been cited as an example in terms of health reforms and developing Primary Health Care, this study highlights the challenge of managing conditions that are viewed as "too complicated" for non-specialists and the impact this has on costs and management of individuals.

Promoting independence, health and well-being for older people: a feasibility study of computer-aided health and social risk appraisal system in primary care.

BACKGROUND: With population ageing, research is needed into new low-cost, scalable methods of effective promotion of health and wellbeing for older people. We aimed to assess feasibility, reach and costs of implementing a new tailored computer-aided health and social risk appraisal system in primary care. METHODS: Design: Feasibility study. SETTING: Five General Practices in London (Ealing) and Hertfordshire, United Kingdom (UK) Participants: Random sample of patients aged 65 + years. INTERVENTION: The Multi-dimensional Risk Appraisal for Older people (MRA-O) system includes: 1) Postal questionnaire including health, lifestyle, social and environmental domains; 2) Software system generating a personalised feedback report with advice on health and wellbeing; 3) Follow-up of people with new concerning or complex needs by GPs or practice nurses. EVALUATION: Feasibility of implementation; participant wellbeing, functional ability and quality of life; social needs, health risks, potential lifestyle changes; and costs of implementation. RESULTS: Response rates to initial postal invitations were low (526/1550, 34%). Of these, 454/526 (86%) completed MRA-O assessments. Compared to local UK Census data on older people, participants were younger, more were owner-occupiers and fewer were from ethnic minority groups than expected. A range of problems was identified by participants, including pain in last week (269/438, 61.4%), low physical activity (173/453, 38.2%), sedentary lifestyle (174/447, 38.3%), falls (117/439, 26.7%), incontinence (111/441 25.2%), impaired vision 116/451 (25.7%), impaired hearing (145/431, 33.6%), depressed mood (71/451, 15.7%), impaired memory (44/444 9.9%), social isolation (46/449, 10.2%) and loneliness (31/442, 7.0%). Self-rated health was good/excellent in 312/437 (71.4%), and quality of life and well-being were slightly above age-specific population norms. Implementation costs were low. Practices reviewed medical records of 143/454 (31.5%) of participants as a consequence of their responses, and actively followed up 110/454 (24.2%) of their patients. CONCLUSIONS: A computer-aided risk appraisal system was feasible for General Practices to implement, yields useful information about health and social problems, and identifies individual needs. Participation rates were however low, particularly for the oldest old, the poorest, and ethnic minority groups, and this type of intervention may increase inequalities in access. Widespread implementation of this approach would require work to address potential inequalities.

Estimating the cost of caring for people with cancer at the end of life: A modelling study.

BACKGROUND: People with advanced cancer require a range of health, social and informal care during the final phases of life. The cost of providing care to this group as they approach the end of their lives is unknown, but represents a significant cost to health and social care systems, charities patients and their families. AIM: In this study, we estimate the direct and indirect costs for lung, breast, colorectal and prostate cancer patients at the end of life (from the start of strong opioids to death) in England and Wales. METHODS: We use a modelling-based approach to estimate the costs of care. Data are estimated from the literature and publicly available data sets. Probabilistic sensitivity analysis is used to reflect uncertainty in model estimates. RESULTS: Total estimated costs for treating people with these four cancers at the end of life are £ 641 million. Breast and prostate cancer patients have the highest expected cost per person at £ 12,663 (95% credible interval (CI): £ 1249-£ 38,712) and £ 14,859 (95% CI: £ 1391-£ 46,424), respectively. Lung cancer has the highest expected total cost (£ 226 m). The value of informal care giving accounts for approximately one-third of all costs. CONCLUSION: The cost to society of providing care to people at the end of their lives is significant. Much of this cost is borne by informal care givers. The cost to formal care services of replacing this care with paid care giving would be significant and demand for care will increase as the demographic profile of the population ages.

An early evaluation of clinical and economic costs and benefits of implementing point of care NAAT tests for Chlamydia trachomatis and Neisseria gonorrhoea in genitourinary medicine clinics in England.

OBJECTIVES: To estimate the costs and benefits of clinical pathways incorporating a point of care (POC) nucleic acid amplification test (NAAT) for chlamydia and gonorrhoea in genitourinary medicine (GUM) clinics compared with standard off-site laboratory testing. METHOD: We simulated 1.2 million GUM clinic attendees in England. A simulation in Microsoft Excel was developed to compare existing standard pathways of management for chlamydia and gonorrhoea with a POC NAAT. We conducted scenario analyses to evaluate the robustness of the model findings. The primary outcome was the incremental cost-effectiveness ratio. Secondary outcomes included the number of inappropriate treatments, complications and transmissions averted. RESULTS: The baseline cost of using the point of POC NAAT was £103.9 million compared with £115.6 million for standard care. The POC NAAT was also associated with a small increase of 46 quality adjusted life years, making the new test both more effective and cheaper. Over 95 000 inappropriate treatments might be avoided by using a POC NAAT. Patients receive diagnosis and treatment on the same day as testing, which may also prevent 189 cases of pelvic inflammatory disease and 17 561 onward transmissions annually. DISCUSSION: Replacing standard laboratory tests for chlamydia and gonorrhoea with a POC test could be cost saving and patients would benefit from more accurate diagnosis and less unnecessary treatment. Overtreatment currently accounts for about a tenth of the reported treatments for chlamydia and gonorrhoea and POC NAATs would effectively eliminate the need for presumptive treatment.

Behavioural and psychiatric symptoms in people with dementia admitted to the acute hospital: prospective cohort study.

BACKGROUND: Dementia is common in older people admitted to acute hospitals. There are concerns about the quality of care they receive. Behavioural and psychiatric symptoms of dementia (BPSD) seem to be particularly challenging for hospital staff. AIMS To define the prevalence of BPSD and explore their clinical associations. METHOD: Longitudinal cohort study of 230 people with dementia, aged over 70, admitted to hospital for acute medical illness, and assessed for BPSD at admission and every 4 (± 1) days until discharge. Other measures included length of stay, care quality indicators, adverse events and mortality. RESULTS: Participants were very impaired; 46% at Functional Assessment Staging Scale (FAST) stage 6d or above (doubly incontinent), 75% had BPSD, and 43% had some BPSD that were moderately/severely troubling to staff. Most common were aggression (57%), activity disturbance (44%), sleep disturbance (42%) and anxiety (35%). CONCLUSIONS: We found that BPSD are very common in older people admitted to an acute hospital. Patients and staff would benefit from more specialist psychiatric support.

A framework for understanding quality of life in individuals without capacity.

PURPOSE: The wide range of tools and methods developed for measuring and valuing health-related quality of life for use in economic evaluations are appropriate for use in most populations. However, for certain populations, specific tools may need to be developed to reflect the particular needs of that population. Patients without capacity--particularly patients with severe dementia--are such a population. At present, the tools available to economists for measuring and valuing quality of life in these patients lack validity. Here, we seek to understand the framework within which common instruments have been developed, critique these instruments with respect to patients with severely restricted capacity and to develop a new way of thinking about how to value health-related quality of life in such patients. METHOD: In this essay, we describe and critique the conceptual framework by which common instruments used for measuring and valuing quality of life have been developed. RESULTS: We show that current common instruments used for measuring and valuing quality of life in general populations are not appropriate for populations with severely restricted capacity. CONCLUSIONS: We propose a new framework for thinking about quality of life in this population, based on notions of observable person-centred outcomes and utility derived from processes of care.

A cost-utility analysis of a rehabilitation service for people living with and beyond cancer.

BACKGROUND: We conducted a wait-list control randomised trial of an outpatient rehabilitation service for people living with and beyond cancer, delivered in a hospice day care unit. We report the results of an economic evaluation undertaken using the trial data. METHODS: Forty-one participants were recruited into the study. A within-trial stochastic cost-utility analysis was undertaken using Monte-Carlo simulation. The outcome measure for the economic evaluation was quality adjusted life years (QALYs). Costs were measured from the perspective of the NHS and personal social services. Uncertainty in the observed data was captured through probabilistic sensitivity analysis. Scenario analysis was conducted to explore the effects of changing the way QALYs were estimated and adjusting for baseline difference in the population. We also explore assumptions about the length of treatment benefit being maintained. RESULTS: The incremental cost-effectiveness ratio (ICER) for the base-case analysis was £14,231 per QALY. When QALYs were assumed to change linearly over time, this increased to £20,514 per QALY at three months. Adjusting the estimate of QALYs to account for differences in the population at baseline increased the ICER to £94,748 per QALY at three months. Increasing the assumed length of treatment benefit led to reduced ICERs in all scenarios. CONCLUSIONS: Although the intervention is likely to be cost-effective in some circumstances, there is considerable uncertainty surrounding the decision to implement the service. Further research, informed by a formal value of information analysis, would reduce this uncertainty.

Capturing Valuation Study Sampling Uncertainty in the Estimation of Health State Utility Values Using the EQ-5D-3L.

OBJECTIVES: Utility scores associated with preference-based health-related quality-of-life instruments such as the EQ-5D-3L are reported as point estimates. In this study, we develop methods for capturing the uncertainty associated with the valuation study of the UK EQ-5D-3L that arises from the variability inherent in the underlying data, which is tacitly ignored by point estimates. We derive a new tariff that properly accounts for this and assigns a specific closed-form distribution to the utility of each of the 243 health states of the EQ-5D-3L. METHODS: Using the UK EQ-5D-3L valuation study, we used a Bayesian approach to obtain the posterior distributions of the derived utility scores. We constructed a hierarchical model that accounts for model misspecification and the responses of the survey participants to obtain Markov chain Monte Carlo (MCMC) samples from the posteriors. The posterior distributions were approximated by mixtures of normal distributions under the Kullback-Leibler (KL) divergence as the criterion for the assessment of the approximation. We considered the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm to estimate the parameters of the mixture distributions. RESULTS: We derived an MCMC sample of total size 4,000 × 243. No evidence of nonconvergence was found. Our model was robust to changes in priors and starting values. The posterior utility distributions of the EQ-5D-3L states were summarized as 3-component mixtures of normal distributions, and the corresponding KL divergence values were low. CONCLUSIONS: Our method accounts for layers of uncertainty in valuation studies, which are otherwise ignored. Our techniques can be applied to other instruments and countries' populations. HIGHLIGHTS: Guidelines for health technology assessments typically require that uncertainty be accounted for in economic evaluations, but the parameter uncertainty of the regression model used in the valuation study of the health instrument is often tacitly ignored.We consider the UK valuation study of the EQ-5D-3L and construct a Bayesian model that accounts for layers of uncertainty that would otherwise be disregarded, and we derive closed-form utility distributions.The derived tariff can be used by researchers in economic evaluations, as it allows analysts to directly sample a utility value from its corresponding distribution, which reflects the associated uncertainty of the utility score.

Utilization of early supported discharge and outpatient rehabilitation services following inpatient stroke rehabilitation.

BACKGROUND: Studies examining factors associated with patient referral to early supported discharge (ESD)/outpatient rehabilitation (OPR) programs and utilization of ESD/OPR services after discharge from inpatient stroke rehabilitation (IPR) are scarce. Accordingly, we examined utilization of ESD/OPR services following discharge from IPR and patient factors associated with service utilization. METHODS: Stroke patients discharged from IPR facilities in Alberta between April 2014 and March 2016 were included and followed for one year for ESD/OPR service utilization. Multivariable linear and negative binomial regressions were used to examine association of patients' factors with ESD/OPR use. RESULTS: We included 752 patients (34.4% of 2,187 patients discharged from IPR) who had 40,772 ESD/OPR visits during one year of follow-up in the analysis. Mean and median ESD/OPR visits were 54.2 and 36 visits, respectively. Unadjusted ESD/OPR visits were lower in females and patients aged ≥ 60 years but were similar between urban and rural areas. After adjustment for patient factors, patients in urban areas and discharged home after IPR were associated with 83.5% and 61.9%, respectively, increase in ESD/OPR visits, while having a right-body stroke was associated with 23.5% increase. Older patients used ESD/OPR less than their younger counterparts (1.4% decrease per one year of older age). Available factors explained 12.3% of variation in ESD/OPR use. CONCLUSION: ESD/OPR utilization after IPR in Alberta was low and varied across age and geographic locations. Factors associated with use of ESD/OPR were identified but they could not fully explain variation of ESD/OPR use.