Measuring What Matters Most in Aortic Stenosis: Is It Time for Disease-Specific Measurement?

Patient-reported outcomes (PROs) defined by the US Food and Drug Administration as “any report of the status of a patient’s health condition that comes directly from the patient, without interpretation of the patient's response by a clinician or anyone else” [1], are increasingly being used within research in cardiology as one way of obtaining and reporting patients’ own perspectives of their health [2]. PROs commonly include, e.g., symptom burden, quality of life (QoL), and mental health – all domains highly relevant to assess in the AS population. When considering treatment for AS, decreased symptom burden and increased QoL are key factors to motivate patients, in addition to reducing the mortality risk [3]. To capture this, the only source of data is the patient. These perspectives can be accurately and reliably assessed with PRO measurements (PROMs), focussing on both generic aspects of health and disease-specific or domain-specific health status [3].

In their narrative review “Quality of Life Measures in Aortic Stenosis Research,” Frank et al. [4] provide an overview of PROMs used in research to measure QoL in patients with AS. The authors identified 79 studies in which eight PROMs were used: the generic Short Form Health Survey (SF-36/SF-12), EuroQol-5D (EQ-5D), and Illness Intrusiveness Rating Scale (IIRS), and the cardiac-specific HeartQoL, Kansas City Cardiomyopathy Questionnaire (KCCQ), Minnesota Living with Heart Failure Questionnaire (MLHF), MacNew Questionnaire, and Toronto Aortic Stenosis Quality of Life Questionnaire (TASQ). The investigators highlight that the TASQ was the only available instrument developed specifically for patients with AS. They provide important insights about the unique experience of patients with valvular heart disease that are not fully accounted for in instruments developed to measure heart failure patients’ health status. In addition, the authors argue how incorporating QoL measures in clinical practice should be an “add-on” to clinical measures to facilitate and optimize the effectiveness of treatment. Lastly, they stress that consensus on “which instrument to use in routine clinical practice of AS treatments is lacking.” We could not agree more and echo their call to action to overcome the barriers to routinely measure and consider PROMs to advance the care of people with AS.

To achieve this goal, there is still important work to be done to strengthen the rigour of measurement to effectively and reliably assess PROs. In spite of multiple initiatives driving the acceptance of PROMs – mandatory inclusion in many trial designs, adoption in large administrative registries, condition of reimbursement, or integration in clinical processes – there is limited evidence investigating the psychometric properties of most instruments in patients with AS. Although generic instruments allow for comparison across patient populations, the individual changes before and after treatment should, preferably, be measured with an instrument specifically developed for the population. Disease-specific instruments are more likely to be sufficiently sensitive to capture minimally clinically important differences during the trajectories of disease progression, treatment, and follow-up, whether this is in the context of younger patients undergoing surgical aortic valve replacements or older patients treated with transcatheter aortic valve implantation. Why is this important? When investigating differences in outcomes across treatment options or patient groups, we commonly compare their outcomes on treatment risks, mortality, stroke, readmissions, and the need for repeated surgery. The recent results of the PARTNER 3 trial, which demonstrated that transcatheter aortic valve implantation was superior to surgical aortic valve replacements in low-risk patients in reducing death, stroke, or rehospitalization, also reported that the effect on health status measured with the KCCQ was modest, although significant, after 1 year. Although the KCCQ has undergone validation in the AS population [5], these findings raise the question of whether the measurement of PROMs in people with AS could be further refined to strengthen this important assessment and possibly better capture changes in health status. The efforts invested in developing the TASQ to address this issue may yield future options. As discussed in the narrative review, recommendations for adoption are currently thwarted by the gap in psychometric evaluation required to give clinicians and researchers the confidence to endorse its use. Thus, we now face a challenging situation: the KCCQ has been somewhat “retrofitted” from the heart failure to the AS population and has been widely used in seminal studies and incorporated in large national registries; it has demonstrated significant value in measuring change over time and has become a benchmark comparator. Is this good enough, or should we persevere with initiatives such as the TASQ – or develop and test others – to better match the PROM to the unique aspects of the health status of people with valvular heart disease?

As Frank et al. [4] elegantly highlight in their review, there are exciting opportunities to advance this field of research and promote the integration of patients’ perspectives in the treatment of AS and other valvular heart disease. Patients and their families, advocacy organizations, clinicians, researchers, and policymakers have a shared investment in supporting this agenda. The goal of “getting PROMs right” will serve us well to move forward on multiple exciting initiatives. For example, PROMs are integral to supporting the implementation of shared decision-making and the increasing availability of patient decision aids that outline clinician- and patient-reported benefits of treatment to evaluate risk and consider patients’ values, preferences and priorities [3]. Similarly, the consideration of PROMs in registry-based evaluation will be essential in the context of rapidly evolving indications for the treatment of valvular heart disease to monitor quality of care. Lastly, supporting clinicians to learn how to use PROMs to augment clinical assessments will contribute to shifting the culture of care from clinician-driven to patient-centred and achieving improved outcomes, both from the perspectives of clinicians and those for whom this is the biggest concern, the patients. Thus, the time has come to measure what matters most to AS patients – with relevant, disease-specific, and validated instruments. The next step will be to choose which instrument this is.