Cost-Effectiveness Analysis: Treatment Initiation Threshold for People with Stage 1 Hypertension
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National Institute for Health and Care Excellence FINAL Hypertension in adults: diagnosis and management Cost-effectiveness analysis: Treatment initiation threshold for people with stage 1 hypertension NICE guideline NG136 Economic analysis report August 2019 Final This guideline was developed by the National Guideline Centre Hypertension in adults: FINAL Contents Disclaimer The recommendations in this guideline represent the view of NICE, arrived at after careful consideration of the evidence available. When exercising their judgement, professionals are expected to take this guideline fully into account, alongside the individual needs, preferences and values of their patients or service users. The recommendations in this guideline are not mandatory and the guideline does not override the responsibility of healthcare professionals to make decisions appropriate to the circumstances of the individual patient, in consultation with the patient and, where appropriate, their carer or guardian. Local commissioners and providers have a responsibility to enable the guideline to be applied when individual health professionals and their patients or service users wish to use it. They should do so in the context of local and national priorities for funding and developing services, and in light of their duties to have due regard to the need to eliminate unlawful discrimination, to advance equality of opportunity and to reduce health inequalities. Nothing in this guideline should be interpreted in a way that would be inconsistent with compliance with those duties. NICE guidelines cover health and care in England. Decisions on how they apply in other UK countries are made by ministers in the Welsh Government, Scottish Government, and Northern Ireland Executive. All NICE guidance is subject to regular review and may be updated or withdrawn. Copyright © NICE 2019. All rights reserved. Subject to Notice of rights. Hypertension in adults: FINAL Contents Contents 1 Cost-effectiveness analysis: treatment initiation threshold for people with stage 1 hypertension .................................................................................................... 5 1.1 Introduction ........................................................................................................... 5 1.2 Methods ................................................................................................................ 5 1.2.1 Model overview .......................................................................................... 5 1.2.2 Approach to modelling ............................................................................... 6 1.2.3 Model inputs ............................................................................................ 11 1.2.4 Sensitivity analyses .................................................................................. 37 1.2.5 Computations ........................................................................................... 47 1.2.6 Model validation ....................................................................................... 48 1.2.7 Estimation of cost effectiveness ............................................................... 48 1.2.8 Interpreting Results .................................................................................. 48 1.3 Results ................................................................................................................ 48 1.3.1 Base case ................................................................................................ 48 1.3.2 Sensitivity analyses .................................................................................. 53 1.4 Discussion ........................................................................................................... 63 1.4.1 Summary of results .................................................................................. 63 1.4.2 Limitations and interpretation ................................................................... 64 1.4.3 Generalisability to other populations or settings ....................................... 66 1.4.4 Comparisons with published studies ........................................................ 66 1.4.5 Conclusions ............................................................................................. 66 1.4.6 Implications for future research ................................................................ 67 4 Hypertension in adults: FINAL 1 Cost-effectiveness analysis: treatment initiation threshold for people with stage 1 hypertension 1.1 Introduction One of the key clinical issues explored in the 2019 guideline update was the threshold for initiation of antihypertensive drug treatment in terms of either blood pressure (BP) or cardiovascular (CV) risk. The clinical evidence review identified evidence relating to different blood pressure thresholds, but no evidence was identified relating to cardiovascular risk. The committee agreed there was evidence to suggest relative treatment benefit in people with stage 1 hypertension (systolic BP 140–159 mmHg), in terms of reducing cardiovascular events. But there was uncertainty about cost effectiveness in this population because the same relative treatment benefit would lead to different absolute benefits in people with lower cardiovascular risk compared to people with higher cardiovascular risk, and because of potential competing risks especially at low absolute cardiovascular risk. The 2011 recommendations for treatment initiation amongst those with stage 1 hypertension incorporate a cardiovascular risk based component, which was based on consensus: • Offer antihypertensive drug treatment to people aged under 80 years with stage 1 hypertension who have one or more of the following: o target organ damage o established cardiovascular disease o renal disease o diabetes o a 10-year cardiovascular risk equivalent to 20% or greater. [new 2019] Given the evidence identified for different blood pressure initiation thresholds and the fact that the previous risk-based recommendation was consensus based, the committee agreed that it was a high priority to evaluate at which risk level it is cost effective to initiate antihypertensive drug treatment in people with stage 1 hypertension without target organ damage, established cardiovascular disease (CVD), renal disease or diabetes. A similar evaluation was recently undertaken as part of the NICE lipids guideline update and so it was agreed that it would be appropriate to take a similar approach for this guideline. 35 1.2 Methods 1.2.1 Model overview A cost–utility analysis was undertaken where lifetime quality-adjusted life-years (QALYs) and costs from a current UK NHS and personal social services perspective were considered. Both costs and QALYs were discounted at a rate of 3.5% per annum in line with NICE methodological guidance.38 An incremental analysis was undertaken. 1.2.1.1 Comparators The comparators in the analysis were: • Antihypertensive drug treatment © NICE 2019. All rights reserved. Subject to Notice of rights. 5 Hypertension in adults: FINAL • No antihypertensive drug treatment The comparators were compared in the following 10-year QRISK cardiovascular risk subgroups to assess whether it is cost effective to use antihypertensive drug treatment in each risk group: • 5% • 10% • 15% • 20% Note that QRISK2 was specified as it is recommended by NICE for risk calculation at the time of guideline development, and it was assumed it was most likely to be used to assess risk in practice. However, that risk was pre-defined for the subgroups and was not calculated in the model using the tool. Minimum possible risk levels for particular age and sex groups were, however, calculated using QRISK2 to aid interpretation of the results (this is discussed in section 1.2.4.1). However given the recent release of QRISK3, a comparison of minimum risk levels using both versions are reported in the results section to assess any changes in the interpretation of the model results. 1.2.1.2 Population The population considered in the analysis was adults with primary stage 1 hypertension (BP 135/85mmHg and above and below 150/95 mmHg on ambulatory blood pressure monitoring [ABPM]), who do not have target organ damage, established CVD, renal disease or diabetes. In the base-case analysis, the model was run using a starting age of 60 for both men and women. This was considered to be a typical age at diagnosis of stage 1 hypertension (as identified from analysis of the Health Survey for England 2006,45 for those with untreated stage 1 hypertension between the ages of 35–80). Alternative starting ages (age 40, 50, 60, 70, and 75) were analysed in sensitivity analyses within each risk subgroup and by sex. An analysis was not run for people under 40. Hypertension is less frequent in people under 40, and the committee highlighted that there are other considerations when deciding about initiating treatment, such as the abnormal nature of this occurring, often related to secondary causes or strong family histories of premature hypertension and it was felt to more likely require treatment on an individual basis. An analysis was not run for a starting age of 80 because this population was not included as part of the recommendation relating to this model, as there are also other considerations when initiating treatment in people over 80, such as their inherent higher risk, frailty and other comorbidities. A separate consensus based recommendation was made for this group considering these factors. The