Download Quality of life in the veterinary cancer patient is a multi

VETERINARY COOPERATIVE ONCOLOGY GROUP CONSENSUS STATEMENT ON HEALTH RELATED
QUALITY OF LIFE ASSESSMENT IN THE VETERINARY CANCER PATIENT
A.E .Hershey, A.L. Garcia, M. Giuffrida, M.J. Hamilton, B Kitchell, T. LaDue, R. Palmquist, D. O’Brien, J.
Reid, K. Rissetto, L.M. Troutman, J Wypij
Abstract: The purpose of this report is to offer a consensus opinion of members of the Veterinary
Cooperative Oncology Group and American Holistic Veterinary Medical Association regarding
assessment and validation of quality of life in veterinary patients with cancer.
Background:
Quality of life (QoL) in people is a multi-dimensional concept that includes subjective evaluation
of both positive and negative aspects of life,1,2 i.e. a person’s sense of “well-being.” Quality of life
includes social and emotional as well as physical aspects of a person’s life. It can be challenging to
measure in that although “quality of life” has meaning for nearly everyone, individuals or groups may
define it differently. In health care, health related quality of life (HRQoL) is an assessment of how a
person’s well-being may be affected over time by a disease, disability or disorder.3
Health related quality-of –life (HRQoL) has evolved since the 1980s in humans to include evaluation of
those aspects of health care that influence both physical, mental, and spiritual health. As advances in
human medicine have led to better treatment of diseases and delayed mortality, it has become
important to not only assess a population’s health in terms of lives saved, but also on the improvement
of quality of life of those treated.
In humans, HRQoL can be evaluated on the individual level in terms of physical and mental health
perceptions including health risks, functional status, social support and socioeconomic status. HRQoL
can also be defined in terms of community level including resources, policies, procedures and practices
that influence a population’s health perceptions and functional status. This construct enables health
agencies to effectively address broader health public policy in collaboration with wider circle of health
partners including social service agencies, business groups and community planners.4
HRQoL questionnaires on perceived mental and physical health have become an important part of
health surveillance in humans and are generally considered valid measures of health service needs and
intervention outcomes. Self-assessment of health status in humans has proved to be a more powerful
predictor of morbidity and mortality than many objective measures of health.5,6
Definition of Quality of Life in Pet Animals:
Quality of life in pet animals may be defined as the perception by a pet caretaker of a pet’s overall
enjoyment of life including the perception of a pet’s “well-being” and its ability to carry out various
activities in context of the pet’s normal daily patterns and expected abilities. This definition will allow
for differences in a pet’s expected activity or performance based on their “occupation” as companion
animal, service or working animal or performance/sporting animal. Quality of life in animals also
comprises dimensions of physical, social and emotional well-being.
Determination of QoL in pet animals emphasizes the owner’s perception on the animal’s QoL rather
than how the animal feels about its circumstances, i.e. a personal experience. The owner can only
report on behavioral changes and other causal variables such as vomiting, diarrhea, etc.
Purpose of the evaluation of QoL in the veterinary cancer patient:
It is important to track the QoL in veterinary cancer patients for several reasons. Cancer is now the
leading cause of death in older dogs7 and one of the most common causes of death in cats.8 Many pet
owners consider their pets members of the family and seek the same level and quality of care expected
for human family members.
Evaluation of QoL allows for improvement in overall patient care and determination of the value of
healthcare services. Evaluation of QoL can also improve or guide treatment decisions for both the client
and veterinarian. Quality of life is an ever-growing concern for the pet owner and will often impact the
decision making of a client when faced with treating a pet with cancer. Most owners are more
concerned with quality of life versus quantity and would prefer improved quality of life over “time.”
Evaluation of QoL in the individual veterinary cancer patient will help veterinarians to track changes in a
patient over time including the impact of certain treatments and the deterioration in patient condition
as the cancer progresses. Assessment of QoL will help clinicians alter treatments to better improve a
patient’s quality of life and assist owners in making decisions regarding euthanasia or end of life care.
Evaluation of QoL in groups of veterinary cancer patients will allow veterinarians to track
improvements, or lack thereof, in specific cancer therapies and whether these therapies are resulting in
improved treatment outcome over time. This can lead to development of additional treatments,
including holistic and alternative therapies that can improve QoL for veterinary cancer patients.
Criteria for Evaluation of QoL in the Veterinary Cancer Patient:
Quality of life in the veterinary cancer patient is a multi-dimensional subjective concept. Criteria for the
evaluation of QoL in the veterinary cancer patient will include a combination of physical functions, pain
assessment, social interactions and emotional perception.
Physical functions: Evaluation of physical functions of the veterinary cancer patient should include
appetite, mobility, energy level, presence of gastrointestinal (GI) signs, urination habits and weight of
the patient as below:
Appetite: increased, normal, decreased, finicky, anorectic
Mobility: increased, normal, decreased, immobile
Energy Level: increased, normal, decreased, listless
Gastrointestinal signs: none present, vomiting, belching, flatulence, diarrhea, constipation,
tenesmus
Urination: normal, increased production, decreased production, painful, straining, bloody
Weight: Weight loss, weight gain, cachexia, assignment of body condition score
Pain assessment:
The ability to recognize and adequately assess pain in the veterinary cancer patient is essential in the
management of the disease. Pet owners are increasingly concerned with how much pain their pet may
be experiencing. In humans, at least half of the patients with malignant cancer are experiencing pain
and two-thirds have pain severe enough to interfere with sleep, mood, social interactions, and activities
of daily living.9
Pain in the cancer patient often occurs from the tumor compressing or infiltrating into surrounding
tissues or from skin, nerve and other changes caused by hormone imbalance or immune response. The
presence of pain often depends on the type, location, and stage of the cancer as well as the pain
tolerance (manifestation of pain) of the individual animal. Treatments such as surgery, radiation therapy
and/or chemotherapy may also cause pain in the cancer patient. Most chronic pain in the cancer
patient is caused by the cancer itself where acute pain is more often caused by treatment or diagnostics.
However, in some patients radiation and chemotherapy can cause painful side effects that persist long
after treatment has ended.10-11
Pain is now considered to be the fourth vital sign- after temperature, pulse, and respiration (the fifth
vital sign in humans after blood pressure) and should be integrated into patient evaluations such that
the veterinarian can recognize, assess, prevent and treat pain.12 Although traditionally pain has been
categorized into acute or chronic pain based on duration, the more contemporary approach is to
consider pain as either adaptive or maladaptive. Adaptive pain is a normal response to tissue damage.
Adaptive pain includes inflammatory pain which is a major component of many pain states including
acute pain that occurs with surgery or trauma. Inflammatory pain may also occur in chronic pain states
such as osteoarthritis or cancer. If adaptive pain is not appropriately managed, physical changes occur
in the spinal cord and brain leading to pain that is termed maladaptive. Maladaptive pain includes
neuropathic and central pain. Pain induced changes can occur in the nervous system that cause it to
become more sensitive rather than less sensitive. The longer pain is unmanaged, the more likely the
neurophysiologic processes involved will result in a switch from adaptive to maladaptive pain which is
more serious and difficult to control.12
Recognizing pain in animals can be difficult. In non-verbal patients (such as animals), the assessment of
pain relies on the observations of the caregiver that knows the patient well. Measurement of objective
physiologic parameters (temperature, heart rate, etc.) has proven to be unreliable as indicators of pain
because of the influence of non-pain parameters such as stress, distress, anxiety and normal biologic
variation. An observer’s perception of pain is often related to behavioral changes in an individual
animal. Well-being in animals is usually associated with normal species specific behavior. Changes in
behavior (i.e. development of new behaviors or absence of routine behaviors) may be a sign of pain.
The following is a list of signs of pain in animals:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Guarding or protecting an affected area
Self-mutilation/licking at an affected area
Drooling/dysphagia
Change in posture
Lack of grooming
Vocalization
Change in personality
Restlessness
Decreased activity
Isolation from group
Decreased appetite
Physiologic changes such as increased heart rate, increased respiratory rate and
increased temperature, weight loss and dehydration
Pain assessment tools
There are several scoring tools that have been used in animals; however to date there is no
single accepted pain scale that has been developed for use in dogs and cats. A single scoring system for
both dogs and cats is not possible because of the species specific behaviors associated with pain. Scoring
pain in non-verbal patients is a special challenge. Scoring systems should meet the following criteria:
minimization of interobserver variability and bias, ability to distinguish between varying levels of pain
intensity, and the ability to detect the degree of “importance” of pain to the subject. The most
validated and widespread pain scale used in veterinary medicine is the Short form of the Glasgow
Composite Measure Pain Scale (CMPS-SF).13 This scale was designed to measure acute pain only and as
such is unsuitable for use in chronic, painful conditions such as cancer. The assessment of chronic pain
has no gold standard objective measure in either humans or animals, but is generally assessed through
its impact on QoL.
More recently, a novel system was published by The University of Pennsylvania School of Veterinary
Medicine (UPenn). Researchers and clinicians at UPenn published a pain assessment tool called the
Canine Brief Pain Inventory (Canine BPI) which is based on the human Brief Pain Inventory (BPI) in a
canine model of spontaneous bone cancer. 14 Their research concluded that the Canine BPI reliably
measures the same pain constructs in the canine model of spontaneous bone cancer as the BPI does in
people with bone cancer. The CBPI performed well in various tests of validity. Additionally, the severity
and interference scores correlated well with the QoL question such that as pain scores increased,
perceived QoL decreased. The CPI also appears to be responsive to disease progression.
It would be a goal for future research to determine if the Canine BPI was useful for evaluation of pain in
other species and with chronic pain from cancers other than bone cancer.
Social well-being
Social well-being in humans relates to one’s ability to interact in society as a friend, family
member, worker, or citizen or in other ways interacting with others. In animals, this may be interpreted
as an animal’s ability to interact within its “family” of humans and other animals. It may also relate to
an animal’s ability to perform, its “duty” or role within the family as companion, service, or sporting
animal. Many animals will begin to isolate themselves when ill, although others may become very
dependent or “needy.” For pets ill with cancer, these social interactions may change and can be readily
observed by the caregiver.
Emotional well-being
Emotional or mental well-being implies that cognitive functions are intact and that the animal
has no burden of fear, anxiety, depression, stress or other negative emotions. Evaluation of emotional
well-being in animals is more subjective, relying on the caregiver’s perceptions of how the animal
“feels.”
Spiritual well-being
Spiritual well-being is difficult to define and assess in veterinary medicine. In humans, spiritual
health is considered distinct from religion or mental health and is rooted in three primary areas of life
experiences including relationships (self-esteem, healthy connection to others, healthy connection to
higher power), personal values and purpose in life. Physical, mental, and spiritual health are considered
interconnected and can have a profound effect on each other. The importance of spiritual well-being in
coping with a terminal illness is increasingly recognized in humans.15 Spiritual health is an integral
aspect of the development of integrative and holistic therapies.
Tools to assess Quality of life
Assessment of HRQoL is becoming increasingly more important in veterinary medicine for the reasons
outlined above. It is therefore important to develop and validate tools from which data may be
collected and evaluated reliably. In human medicine, structured questionnaires to measure HRQoL are
developed and tested using well-established psychometric methodology.16 The gold standard measure
of human QoL is the self -rated questionnaire.17-19 Where that is not possible (e.g. young children in
whom language has not yet developed and the cognitively impaired adult) the questionnaire relies on
observation of a person who knows the subject well. Similarly, HRQoL questionnaires in veterinary
medicine will rely on observations and perceptions of the animal care-giver.
An ideal assessment tool has utility, i.e. it should be short and easy to complete for the animal caregiver
and be easy to process for the veterinarian. It must also possess the following measurement properties:
validity (the degree to which an instrument measures what it is supposed to measure), reliability ( the
degree to which an instrument can produce consistent results between observers evaluating the same
animal at a point in time and consistent results on different occasions when the animal’s condition does
not change), and responsiveness (an instrument’s ability to detect change over time that is clinically
relevant).
There are currently 2 published questionnaires that attempt to address HRQoL in veterinary cancer
patients. Lynch and colleagues from the Royal (Dick) School of Veterinary Studies developed a “cancer
treatment form” that consists of 23 multiple choice questions divided into domains entitled happiness,
mental status, pain, appetite, hygiene, water intake, mobility and general health This questionnaire
focuses primarily on the physical aspects of quality of life assessment. This questionnaire is a prototype
instrument to measure HRQoL and has not been assessed for validity, reliability, and responsiveness.20
Iliopoulou and colleagues at Michigan University have developed a QoL survey for use in the cancer
chemotherapy setting. This instrument was limited to dogs with disseminated cancers undergoing a
specific cancer treatment, i.e. chemotherapy.21
These current questionnaires are valuable; however, we believe there is a need for a generic
questionnaire for the veterinary cancer patient with a “core” set of species- specific questions that can
then be built upon to assess HRQoL in relation to specific cancer types, and/or specific treatment
modalities. Vetmetrica is a generic tool that already exists for use in the dog that can be further
developed as a disease-specific instrument for veterinary cancer patients. This methodology can be
applied to any species and work on a generic HRQoL instrument for cats is planned for 2015.
Vetmetrica is a web-based questionnaire to measure a dog’s health and well-being.22 Owners respond
to a set of 46 questions delivered online, and the outcome is a quality of life profile for their dog. This
system was originally developed by scientists and veterinarians at the University of Glasgow. This webbased tool was derived from GUVQuest, a structured 109 item paper-based questionnaire to assess
quality of life in dogs with chronic pain. The Vetmetrica instrument comprises 46 items each of which is
rated by dog owners using a 7-point Likert scale (a rating scale). In an initial study owners were
generally able to complete the questionnaire in 5 minutes or less. Responses are used to generate
automatically and instantaneously, by application of an established algorithm, a profile of scores in 4
domains of quality of life: vitality, pain, distress, and anxiety. This instrument is generic and will
measure the effect of a variety of conditions on HRQoL, not just cancer. The generic instrument has
been shown to be valid in a group of canine lymphoma patients (unpublished results). However, the
goal would be to create an additional module of questions to be used with the generic core questions to
develop a disease- specific questionnaire for the assessment of HRQoL in the veterinary cancer patient.
This resulting questionnaire could be further refined to focus on a particular cancer type, depending on
need. The generic core defines how the animal “feels” and is based on indicator variables while the
additional module is likely to focus on causal variables such as presence of nausea, neutropenia, etc.
The advantages of the web-based tool include: web delivery which minimizes respondent bias, a profile
of scores rather than single item global score which allows more in depth understanding and analysis.
This web-based tool measures the whole spectrum of HRQoL from the worst to the best and most
importantly measures HRQoL from the animal’s perspective- focusing on how the animal feels about its
circumstances using the owner as proxy. In essence, it captures the emotional and affective component
of QoL. Such a tool would be invaluable in the daily decision making for clients and clinicians as well as
assessment of HRQoL in cancer clinical trials.
Summary
In summary, QoL for the veterinary cancer patient is an important aspect of caring for a pet with cancer.
A pet’s QoL will affect treatment-related decision for both the owner and treating clinician. Having a
valid and reliable tool for assessing QoL in veterinary cancer patients is important in being able to track
changes in individual patients over time as well as groups of patients to evaluate the overall impact of
therapies. We propose that VetMetrica is such a tool and our efforts should focus on developing a
cancer-specific module that can be used for individual as well as group assessment in clinical trial
setting.
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