Over the past half-century, advances in medical care and public health have dramatically increased life expectancy, shifting the global burden of human illness from infectious to chronic diseases. Indeed, two-thirds of all deaths in the United States are attributable to diseases that are largely preventable through healthy lifestyle choices and routine preventive care.1 Despite this, only half of all adults in the United States use commonly recommended preventive services, and overall use of many preventive services is approximately 60% to 70% of what is clinically recommended.2,3 Concerns about this so-called prevention gap have recently had an impact at the national policy level, with the Patient Protection and Affordable Care Act reducing barriers to preventive health services and increasing resources for disease prevention, early disease detection, and management of chronic conditions.
Veterinary medicine is in the midst of a similar health crisis but without a similar comprehensive solution. Over the past decade, increases in the prevalence of several common diseases among companion animals have largely mirrored increases in the prevalence of similar diseases in humans.4–6 For example, from 2007 through 2011, prevalences of diabetes mellitus among dogs and cats evaluated at a network of > 800 veterinary hospitals across the United States increased 32% and 16%, respectively, and prevalences of overweight and obesity increased 37% and 90%, respectively. Such increases are of particular concern because many of the most common health conditions in dogs and cats, such as dental disease, overweight and obesity, diabetes mellitus, heartworm disease, flea infestation, and behavioral issues, are largely avoidable through routine preventive care.4–7 The increase in the prevalence of these common diseases coincides, perhaps not surprisingly, with a decade-long decrease in the annual number of veterinary visits for dogs and cats.8 Taken as a whole, the data suggest the existence of a prevention gap similar to that in human medicine, with many pets not receiving care that would help them maintain an optimal level of health.
Problems underlying the veterinary disease prevention gap are similar to those underlying the human disease prevention gap, including difficulties in identifying and effecting needed behavior changes, inability or unwillingness to invest in preventive care, and skepticism about the effectiveness of preventive measures.8,9 Despite these similarities, solutions to the 2 problems are likely quite different, given the lack of a governmental role in companion animal health care.
The Canine and Feline Preventive Healthcare Guidelines10 introduced by the AVMA and American Animal Hospital Association represent an important step by the profession to directly address the difficulties many pet owners face in understanding the preventive health care needs of their pets. However, despite these and other initiatives to promote preventive veterinary care, evidence indicates that the recent decrease in veterinary visit frequency is largely due to a lack of understanding and appreciation by pet owners of the need for routine veterinary care.8 This lack of understanding is likely attributable, if not entirely then at least in part, to the dearth of evidence that preventive care has tangible benefits to pets and their owners.
Research is needed, therefore, to determine the impact of preventive health care in animals and to distinguish effective preventive health-care services from less effective and ineffective ones. However, research into the impact of preventive health care on patient health and well-being, particularly research that is retrospective in nature, is complicated by detection bias that arises when outcomes such as disease development are compared between patients evaluated on a regular (eg, semiannual) basis and those evaluated on a less frequent basis. Certain diseases will be identified more frequently in patients that are followed up more closely or that receive more frequent diagnostic testing than in patients that are monitored less closely.11 Of course, these diseases may still be present, whether clinically or subclinically, in animals that are monitored less closely; they simply are not detected or documented. Thus, retrospective reviews of medical records will likely show higher apparent prevalences of diseases in pets regularly brought in for veterinary care than in those that are not. And, to further complicate matters, outcomes such as a return to health or disease avoidance are rarely if ever recorded in medical records, whereas disease conditions are considerably more likely to be documented. For these reasons, although medical records can be useful for research when the outcome is disease, they are not useful when the outcome is health.
Quality-of-life (QOL) evaluations can help capture important information on health and well-being that is often not included in medical records and not reflected in traditional outcome measures such as morbidity and mortality rates, and QOL assessments specifically related to pet wellness could potentially help advance research on the impact of preventive health-care services. We suggest, therefore, that in conjunction with its preventive health-care initiatives, the veterinary profession should develop a tool for assessing wellness-related QOL.
Definition of QOL
Most people have a general understanding of what is meant by the term QOL, but QOL is surprisingly difficult to characterize. Owing in part to its widespread application in various social and health science fields, the term QOL lacks a single consistent definition or standardized method of measurement.12 In general, however, QOL is thought to represent a multidimensional construct with subjective as well as objective components.12,13 One of the more commonly used definitions in the health-care field comes from the World Health Organization, which describes QOL as “an individual's perception of their position in life in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards and concerns. It is a broad-ranging concept affected in a complex way by the person's physical health, psychological state, personal beliefs, social relationships and their relationship to salient features of their environment.”13 As this definition suggests, QOL cannot be directly observed or measured; rather, it must be inferred from other variables.14
Quality-of-life assessments have been used in a myriad of ways within the human health-care community. Policy makers have used QOL assessments to track population health, identify service needs, and inform health policy, planning, and practice15; researchers have used QOL assessments in clinical trials as a means of evaluating the effectiveness of various health-care interventions16; and physicians have used QOL assessments to help identify the needs of individual patients, facilitate conversations about care and treatment, and assist with decision making.16
QOL in Veterinary Medicine
Quality-of-life assessment is not new to veterinary medicine. The subject has been reviewed previously, as have the unique factors and challenges that make QOL assessment more difficult in animals than in humans.17–19 Existing measures of QOL in veterinary patients vary greatly in their structure and theoretical underpinnings, although most typically fall within the broad categories of mental state approaches or external parameter approaches.20 Mental state approaches are based on the principle that QOL results from subjective evaluations of external stimuli, such as the balance between pleasant and unpleasant feeling states, and should be measured from the perspective of the individual in question.17 External parameter approaches suggest that QOL can be evaluated objectively by outside observers on the basis of the degree to which an animal's basic, species-specific needs are being met.18 In somewhat of a reconciliation between the 2 approaches, Taylor and Mills19 have defined QOL as
the state of an individual animal's life as perceived by [it] at any one point in time. It is experienced as a sense of well-being which involves the balance between negative and positive affective states and any cognitive evaluation of these, where the animal has the capacity. To some extent, QOL can be predicted by the fulfilment of basic and species specific health, social and environmental needs (and individual preferences for these) and is reflected in the animal's health and behaviour.
As these disparate approaches suggest, no broadly accepted definition of QOL for animals has been settled on, no consensus has been reached regarding the factors that contribute to quality of life, and no established method of assessment has emerged. Many definitions of QOL in animals explicitly acknowledge the importance of pleasant affect, positive experiences, or overall well-being, yet existing veterinary QOL assessment tools typically focus primarily on the adverse effects of disease.21
For example, single indicator assessments of QOL, which ask pet owners to assess their animal's current state of well-being by answering a single Likert-type or visual analogue question (eg, “How would you rate your pet's current QOL?”), have been used as a primary or secondary outcome in a number of studies22–32 involving animals with various diseases, and single indicator assessments are reportedly responsive to treatment progress in dogs with atopic dermatitis,22 osteoarthritis,26 neoplastic haemoperitoneum,25 or laryngeal paralysis30 and in cats with osteoarthritis28 or lymphoma.31 Single indicator assessments have also been shown to have convergent validity with other measurements of treatment progress in dogs, including the Canine Brief Pain Inventory24 and Helsinki Chronic Pain Index.26
More complex QOL assessments also support the notion that owner-perceived QOL can be a valid means of evaluating treatment progress. Multi-indicator assessments commonly include multiple items related to the various domains believed to comprise an animal's QOL, but again, most of these instruments are designed to assess the impact of a specific disease on an animal's QOL. Multi-indicator assessments have been effectively developed for use in dogs with spinal cord injuries,33,34 atopic dermatitis,35–38 pain secondary to cancer,39 chronic pain,40,41 obesity,42 diabetes,43 and heart disease44 and in cats with diabetes45 and heart disease.46 Additionally, several of these disease-specific assessments are able to effectively differentiate between ill pets and healthy control pets.33,37 In contrast, less information is available about whether owner-perceived QOL is a valid assessment in animals with less obvious signs of illness, such as parasitic infections or dental disease, or can be used to evaluate nonphysical aspects of QOL, such as social and psychological needs.
For the veterinary profession to capture QOL data that will offer insight into the effectiveness of various preventive health-care services, it will be important to develop a QOL assessment tool that both encompasses aspects of health and well-being and is credible (ie, reliable and valid), easy to use, and quantitative in nature. In addition to providing a legitimate method for quantifying the value of preventive health-care services in research studies, such a tool could potentially help facilitate QOL discussions between pet owners and clinicians and help clinicians educate owners on how to recognize well-being in their pets.
To the authors' knowledge, no validated QOL assessment tools exist that are designed to quantitatively measure QOL in companion animals from the perspective of their physical and mental well-being. Wojciechowska et al47,48 did develop a questionnaire to assess nonphysical aspects of QOL in pet dogs (eg, satisfaction of basic physical needs, near-normal somatic functioning, satisfaction of instinctual needs, opportunities for pleasure, and an environment with minimal distress). However, they found that although the questionnaire had moderate internal consistency, it was unable to differentiate between healthy dogs and sick dogs.48 The fact that the questionnaire explicitly deemphasized physical characteristics may have resulted in capture of information that was not sensitive to health status. However, aspects included in the questionnaire may contribute more to social and psychological wellness and should not necessarily be discounted in future discussions of QOL.
Other than the questionnaire developed by Wojciechowska et al,47,48 few other non-disease-specific QOL assessment tools exist in veterinary medicine.49–51 Importantly, however, there is evidence to suggest that QOL assessments can be powerful conversation tools for influencing how pet owners think about their pet's health and supporting decision making about a pet's care. Mullan and Main50 developed a QOL screening tool to raise awareness among dog owners and veterinary professionals about the factors that influence QOL in dogs. The four-part questionnaire was designed to collect information about a dog's signalment and life history, available resources, behaviors, and QOL domains. Pet owner enthusiasm for the screening tool was positive. Many participants commented that the questionnaire encouraged them to think about their dog's life in a new way, and several reported making changes to their dog's management as a result of the questionnaire. However, the questionnaire was quite lengthy and completing it was time-consuming, which may preclude its use in a busy clinical practice.
The QOL screening tool developed by Mullan and Main50 was subsequently adapted by Yeates et al51 to create a participatory QOL assessment. The assessment was designed to encourage dog owners who had brought their pet to a veterinarian for a wellness examination to actively participate in the assessment of their dog's QOL and to promote conversations about QOL between pet owners and their veterinarians. The tool consisted of 5 visual analogue scales, each designed to assess the degree to which dogs' needs associated with a given aspect of QOL (ie, body weight, mobility, company of humans, company of other dogs, and veterinary care) were being met. During testing, the tool was found to be associated with an increased number of client-clinician discussions and an increased number of owner-reported decisions to change specific aspects of their pet's care (eg, to measure food intake or to begin flea preventive treatment) when used as part of consultations with a veterinarian who was involved in creation of the tool. When used as part of wellness examinations with veterinarians who had not been involved with its development, the tool was associated with an increased number of client-clinician discussions, but no difference was identified in number of decisions made.
Results indicate that the QOL assessment tool developed by Yeates et al51 can be used as a framework to help identify areas of concern and enhance the effectiveness of wellness examinations. However, additional research is needed regarding the overall impact and applicability of the tool. For example, the increased effectiveness of the tool during examinations with a clinician who was already familiar with the tool may reflect a need for proper training in its use. Additionally, data concerning owner decision making were collected at the time of the original examination only, so it could not be determined whether the tool had any long-term effects on owner decision making. In addition, the tool has not been validated, and because it lacks a quantitative output, it does not provide information that is suitable for tracking health status and cannot be used as an outcome variable in its current form.
An important aspect of QOL assessments in veterinary medicine is that they rely on pet owners acting as proxies on behalf of their pets. The owner-as-proxy structure invariably leads to concerns about reliability because of the subjective nature of such assessments and the lack of consistent training of owners. In particular, QOL assessments that are obtained depend on the ability of owners to accurately assess and convey their pet's experience.18,27 However, pet owners may vary considerably in their behavioral responses to similar stimuli and in their aptitude to recognize and interpret subtle signs.52,53 Furthermore, one's knowledge about pet health and disease is likely to influence one's interpretation of pet behavior. For example, an unpublished survey commissioned by Banfield Pet Hospital of a random sample of 1,000 cat owners and 1,000 dog owners found that a large proportion of respondents were unaware that changes in elimination, exercise tolerance, or eating and drinking could be signs of disease. However, evidence indicates that with proper tool construction and question phrasing, observer ratings can be both reliable and valid, particularly when provided by a person familiar with the animal being observed.54 There is considerable evidence that owner-perceived QOL is an effective means of assessing overall treatment progress for many ailments22,25,28,30,31 when the data are acquired as part of a structured assessment completed in concert with a knowledgeable veterinary professional.
QOL and the Future of Veterinary Medicine
Existing research supports the idea that valid, reliable QOL assessment tools can be developed to evaluate the impact of specific diseases and their treatment on QOL. Less information is available about the validity of generic QOL assessment tools, although they have been demonstrated to be effective in enhancing pet owner consultations. However, most existing QOL assessment tools for use in veterinary medicine have been designed to assess QOL through the lens of health deficiencies. The changing nature of health care makes it increasingly important that a QOL measurement tool be developed that is sensitive to the benefits of preventive health care and capable of quantifying degrees of well-being. However, developing such a tool will require considerable investments of time and money, and developing a wellness-based QOL assessment tool is more easily proposed than accomplished. Yeates and Main20 identified 5 necessary steps in the development of a QOL assessment tool: deciding what variables are important, determining what variables can be assessed, assessing those variables, inferring what is important from the variables, and making a decision about actions or recommendations. To this, we would add that once a tool is developed, rigorous assessments of reliability and validity must be done to ensure that accurate and relevant information is being captured.
Despite the challenges of developing a wellness-based QOL assessment tool, we believe the benefits would be worth the effort. Information on QOL could potentially provide evidence on the effectiveness of preventive health-care services, and QOL discussions during wellness examinations could help engage clients in conversations that would help them better understand and appreciate the value of regular veterinary care. In our experience, many pet owners believe their pets are doing well if disease is not apparent, despite the fact that ailments such as dental disease, parasitic infection, and overweight body condition may be causing their pets discomfort and putting them at risk for worse problems later in life. A conversation about a pet's QOL could help transform the discussion from one of cost savings (eg, whether dental cleaning now will cost less than tooth extractions later) to one of cost-effectiveness (eg, dental cleanings make for a healthier, more content pet). Providing clients with an easier way to conceptualize that impact has the power to transform the way they think about preventive health care.
Importantly, wellness-based QOL assessment tools will not achieve their fullest potential unless the QOL focus extends beyond the hospital walls. A tremendous potential for loss of information currently occurs between veterinary visits, particularly when pet owners seek veterinary care from multiple sources. To remedy this, we propose the concept of QOL check-ins, which could be conducted through social media, personal pet health websites, or email as a means of following up on patients between examinations. Other possible benefits of follow-up QOL assessments include establishing or reinforcing the veterinarian-client-patient relationship, facilitating the tailoring of care to individual pets, providing continuous education of pet owners on signs of health and well-being in pets, and facilitating earlier detection of disease and greater owner compliance.55
Through the Partnership for Preventive Pet Healthcare, veterinarians are being encouraged to expand their roles to ensure companion animals receive essential preventive health-care services throughout those animals' lives. A focus on QOL will provide the profession with a means to facilitate and reinforce this paradigm shift.
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