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Volume 24, Number 12: December 2023

The Metrics of Suffering

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By Lukas Radbruch
Chair, IAHPC Board of Directors

This is the age of evidence-based medicine. Health care systems require proof of efficacy before implementing new interventions. Palliative care has left the pioneer stage and is being implemented as a regular part of health care in an increasing number of countries, and this means that palliative care interventions require evidence for effectiveness similar to any other health care intervention.  

Photo by Tara Devi Labar in Perth, Australia; used with permission.

In low- and middle-income countries, which most often have patchy or no provision of palliative care and extremely restricted health care budgets, evidence is also required to prove that it is worthwhile to invest in such a thing as palliative care in the fierce competition for scarce resources. 

Outcome measures need to be clear, concise & consented

The acquisition of evidence requires consent as well as clear and concise outcome measures for research and clinical practice. In palliative care, patient-reported outcome measures (PROMs) have been described as a gold standard (Antunes et al., 2018). A huge number of PROMs have been developed for individual symptoms as well as for combined screening and assessments. This includes short instruments developed specifically for palliative care, such as the Edmonton Symptom Assessment Score (ESAS) and the Integrated Palliative Outcome Score (IPOS), or instruments adapted to palliative care, such as quality-of-life questionnaires EORTC-QLQ-C15-PAL and FACTI-Pal-14. 

Problems with patient-reported measures

However, there are a few problems with the existing PROMs: there is little consensus or standardization. 

An older review from our group identified more than 500 outcome instruments in palliative and hospice care (Stiel et al., 2012), and a multitude of new instruments have been added since. Palliative care patients often suffer from severe physical and cognitive impairments and often are unable to complete even short questionnaires, requiring proxy assessment by family members or health care professionals instead. More important, patients seem to expect much more from palliative care than just symptom control; they also value communication, shared decision making, trust, and respectful and compassionate care, among others (Collier et al., 2023). These aspects are difficult to capture in short, concise instruments. In addition, patients often want to provide more and other feedback than just ticking boxes on a Likert scale or giving a numerical rating (Collier et al., 2023).

Photo by Piyush Gupta in Lucknow, India; used with permission.
‘How do you feel?’ is not the best question

In consequence, PROMs may be more important for health care professionals than patients. Patients may even complete PROMs based on what they think their health care professionals want to hear, not their own lived experience. When we tried to reduce patient burden by identifying a single quality-of-life screening question, we tested the candidate question in a clinical trial, comparing it to established quality-of-life questionnaires (Stiel et al., 2011). We recruited patients both in the radiotherapy department and the palliative care unit. Astonishingly, we found that the single question, “How do you feel today?”, correlated much better with the physical and function domains than with emotional or social domains in the EORTC-QLQ-C30. It seems that the majority of patients understood this question as a medical question addressing physical-functional aspects specifically. However, correlation of the question with non-physical domains were much higher for patients from the palliative care unit than those from the radiotherapy department, leading to the hypothesis that palliative care may have changed patients’ expectations, allowing them to expect openness in topics other than physical performance when communicating with their physician (Stiel et al., 2011). Consequently, we expanded the single question in a subsequent trial to ‘‘How satisfied are you currently with your physical and emotional well-being?” with better results (Conrad et al., 2017).

Care is more than symptom relief

More recently, patient-reported experience measures (PREMs) have been promoted for palliative care, as they focus less on the patient’s suffering and burden, and more on how they perceive the care they receive (Virdun et al., 2023). However, PREMs are used mostly as an add-on in palliative care research and rarely in clinical practice. 

Despite the drawbacks, it is possible to measure physical symptoms such as pain or breathlessness both in research and in clinical practice. However, palliative care is more than just symptom relief: it strives to relieve physical, psychological, social and spiritual suffering. These emotional and existential dimensions are much harder to assess, given the large range of individual values and preferences. 

Photo by Manisha Singh in Ahmenabad, India; used with permission.
Assessing dimensions of suffering

Many instruments try to assess dimensions of suffering beyond the physical. However, the holistic philosophy of palliative care and the focus on the individual priorities and preferences means that we have to discuss the limits of measurability. Some aspects of suffering, due to their individualistic nature, may resist quantitative measurement. Lederberg and Fitchett summarized the assessment of religion and spirituality with the question, “Can you measure a sunbeam with a ruler?” (Lederberg and Fitchett, 1999).

We have compared this problem to Heisenberg’s principle of uncertainty in particle physics (Peusquens et al., 2021), that it is not possible to measure the speed and the location of a particle exactly at the same time. The act of measuring one impacts the other. If we transfer this principle of uncertainty to palliative care assessment, it could mean that we cannot capture both the characteristics and the intensity of suffering at the same time. If we use standardized, validated instruments to assess intensity, we only measure the items included in the questionnaires. If, alternatively, we interview patients and receive detailed in-depth information about their suffering, it is acquired in a non-standardized way that is difficult to compare with other patients. 

Is there a scale of intolerable suffering?

Consideration of the limits of measurability seems even more important when intolerable or unbearable suffering is discussed, for example, as an indication for palliative sedation or medical aid in dying. A Dutch research group has constructed a scale of unbearable suffering (SOS-V) (Ruijs et al., 2009), asking patients to rate the presence of 69 aspects, and the extent to which each is unbearable. Oddly, the authors require patients to use a Likert scale (not at all unbearable - slightly unbearable - moderately unbearable - seriously unbearable - very seriously unbearable). I understand “unbearable” as a dichotomous key: something either is or isn’t unbearable. Unbearable suffering probably requires a shared assessment by the physician or palliative care team (what options are available?) and the patient (is it unbearable?), as has been described for refractory suffering and palliative sedation (Surges et al., 2023).

The Concept of SHS

The Lancet Commission on Global Access to Palliative Care and Pain Relief, led by Felicia Knaul, introduced the concept of serious health-related suffering (SHS). Suffering is health-related when it is associated with illness or injury of any kind. Health-related suffering is serious when it cannot be relieved without professional intervention and when it compromises physical, social, spiritual and/or emotional functioning (Knaul et al., 2018). SHS has been included in the consensus-based definition of palliative care (Radbruch et al., 2020).

SHS estimates were calculated from publicly available databases: Global Health Estimates of the World Health Organization and the Global Burden of Disease database from Institute of Health Metrics and Evaluation (Knaul et al., 2018). Data were collected for the 20 health conditions or illness groups most likely to generate a need for palliative care, and for 11 physical and four psychological symptoms. Using these data, the Lancet Commission estimated that at least 61 million people experienced SHS in 2015, and 80% of these people lived in low- and middle-income countries.

The concept of SHS is currently being refined, with the aim to make SHS data available for palliative care advocates globally. There is still much more research needed on SHS, for example how well the databases are aligned with real-life clinical data.

Serious health-related suffering 
& the usefulness of SALYS

In spite of all these limitations, there is a great need to measure suffering on a national and international scale in order to show the magnitude of the problem and advocate for change. This is not so much about unbearable suffering in a patient, but rather about avoidable suffering in a population, suffering that could easily be reduced with adequate access to opioids or other essential medicines, for example.

Serious health-related suffering (SHS) can be used for the calculation of suffering-adjusted life years (SALYs), taking into account intensity and duration of a patient’s suffering as well as the value of suffering averted. This would be an innovative addition to the use of quality-adjusted life years (QUALYs) and disability-adjusted life years (DALYs). QUALYs are the product of the years left to live and the quality of life in those years. DALYs are the sum of years of life lost and years lived in disability or disease. While QUALYs and DALYs are useful instruments for younger and healthier persons, elderly, severely ill, or disabled persons could gain few QUALYs or DALYs from interventions. SALYs would not have that disadvantage, as the relief of avoidable suffering would be most prominent in the group of severely ill people. 

Palliative care development 
& the role of opioids 

Considering that opioids can relieve pain and breathlessness in most patients, opioid consumption (or lack thereof) has also been used to assess the prevalence of avoidable suffering and unmet palliative care needs. The Lancet Commission Report on Palliative Care and Pain Relief analyzed the distributed opioid morphine equivalent (DOME) as the quantity that is available for prescription to patients. 

The World Health Organization has included morphine consumption (morphine equivalent, except methadone) per cancer death as an indicator for access to palliative care among the 25 health care indicators suggested in the global framework on noncommunicable diseases (World Health Organization, 2012). The inclusion of a palliative care indicator was a big success of international palliative care advocacy work, but there was also major criticism of the way it was formulated. Many countries do not have cancer registries, and in low-resource settings cancer may not even be diagnosed, so the WHO indicator would overestimate the opioid consumption up to 27-fold compared to a broader indicator using morphine equivalent per death (De Lima et al., 2013). 

Opioid consumption has also been included in the comprehensive set of palliative care development indicators for Latin America (Pastrana et al., 2014). Three of the 15 indicators are related to opioid consumption: opioid consumption per cancer death, opioid consumption per capita, and the number of pharmaceutical establishments that dispense strong opioids per million inhabitants. 


Health care has long focused on cure and survival, with little attention to alleviation of suffering. Palliative care, the fourth pillar in health care (in addition to prevention, cure, and rehabilitation) needs to provide proof of the added value of alleviation of suffering. Concise and consented patient-reported outcome measures are needed both in research and in clinical practice to provide that evidence. SHS estimates are useful for advocacy work on a national and global scale. SALYs may offer a pathway toward health care planning and resource allocation that is less utilitarian and more equitable for vulnerable patient groups. 

However, PROMs, SHS, and SALYs will only capture part of what makes palliative care effective. We need to continue the discussion on the metrics of suffering and the limits of measurability in order to provide the best palliative care for each individual patient, with their specific needs and values. 

Lukas Radbruch has held the chair of Palliative Medicine at the University of Bonn for a decade, is director of the university’s Department of Palliative Medicine, and is a longtime, active researcher. Read his bio.

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