Who Is Rescuing Whom?
2019; Lippincott Williams & Wilkins; Volume: 12; Issue: 10 Linguagem: Inglês
10.1161/circoutcomes.119.005887
ISSN1941-7705
Autores Tópico(s)Urban Green Space and Health
ResumoHomeCirculation: Cardiovascular Quality and OutcomesVol. 12, No. 10Who Is Rescuing Whom? Free AccessEditorialPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyReddit Jump toFree AccessEditorialPDF/EPUBWho Is Rescuing Whom?Dog Ownership and Cardiovascular Health Dhruv S. Kazi, MD, MSc, MS Dhruv S. KaziDhruv S. Kazi Dhruv S. Kazi, MD, MSc, MS, 375 Longwood Ave, 4th Floor, Boston MA 02215. Email E-mail Address: [email protected] Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology, Boston, MA. Division of Cardiology, Beth Israel Deaconess Medical Center, Boston, MA. Harvard Medical School, Boston, MA. Originally published8 Oct 2019https://doi.org/10.1161/CIRCOUTCOMES.119.005887Circulation: Cardiovascular Quality and Outcomes. 2019;12:e005887This article is a commentary on the followingDog Ownership and Survival After a Major Cardiovascular EventDog Ownership and SurvivalSee Articles by Kramer et al and Mubanga et alDogs first arrived in human society well before the agricultural revolution, at a time when we were still hunter-gatherers. The first dogs, arising from wolves,1 were allies in the hunt, assisting in the chase and alerting us to mortal dangers. Dogs that offered greater companionship and were more attentive to the needs of their human partners were more likely to receive food and shelter, setting up a process that selected for traits of friendliness, loyalty, and social curiosity. Over the next 15 000 years or so,2 the bond between canine and human evolved substantially, as did the dog's role as a pet in human society. Today, although many still serve as guard dogs or service animals, the vast majority of dogs in high-income countries live in homes as pets and companions. In 2016, 48 million US households had a total of 77 million dogs, 28% of whom were rescued from animal shelters.3 Although the most populous coastal US states have the greatest number of dogs, rates of dog ownership—defined as a proportion of households with one or more dogs—are highest in the heartland: dogs are members of more than half of all households in Idaho, Montana, Arkansas, Mississippi, and West Virginia. Indeed, dog ownership easily bridges the profound rural-urban sociopolitical chasm in the United States.Much has been written about the effect of dog ownership on mental well-being. Dogs offer companionship, reduce anxiety and loneliness, increase self-esteem, and improve overall mood. Even a single exposure to therapy dogs reduces stress response and pain during pediatric phlebotomy or postarthroplasty physical therapy.4 This positive effect of pets on mental well-being appears to extend to other less-interactive pets: community-dwelling older adults randomized to caring for crickets in a cage showed significant improvements on the Geriatric Depression Scale and the Mini-Mental State Examination at 8 weeks compared with those randomized to health advice.5 Although the mental health benefits of pets in general, and dogs in particular, are well-defined, their effect on physical health is less well understood. Two studies in this issue of Circulation: Cardiovascular Quality and Outcomes address this important question.Kramer et al6 present a systematic review of all prior publications that examined the association of dog ownership with all-cause and cardiovascular mortality.6 They identified 10 studies with a total of 3.8 million participants, with follow-up ranging from 1 to 22 years. Four studies that collectively contributed 99,6% of the study participants were based in Scandinavia and England. The remaining participants were from the United States, Canada, New Zealand, and Australia. The meta-analysis found a 24% reduction in the risk of all-cause death (relative risk, 0.76; 95% CI, 0.67–0.86) and a 31% reduction in the risk of cardiovascular death (relative risk, 0.69; 95% CI, 0.67–0.71). The estimated effect size was largest—with the lowest heterogeneity among studies—among individuals with established cardiovascular disease (relative risk, 0.35; 95% CI, 0.17–0.69).The largest of the studies included in the meta-analysis by Kramer et al6 was by Mubanga et al7 who used the Swedish Nationwide Register to examine the association between dog ownership and mortality. Their work demonstrated that over a 12-year follow-up, dog ownership in Sweden was associated with a significant reduction in all-cause mortality and cardiovascular mortality. In this issue of Circulation: Cardiovascular Quality and Outcomes, the research team builds on their prior work by examining the effect of dog ownership in a subgroup of patients with prior cardiovascular disease.8 Following 181 696 individuals who presented with a myocardial infarction and 154 617 individuals who presented with an ischemic stroke between January 1, 2001 and December 31, 2012, they found a 21% reduction in the risk of death from any cause, after adjusting for demographic, socioeconomic, and available clinical factors (age, sex, marital status, children in the home, latitude of residence, region of birth, income, modified Charlson comorbidity index, and history of previous cardiovascular events). The effect was remarkably consistent across various demographic subgroups but was modified by the number of individuals in the household: single-person households with dogs were associated with a markedly greater reduction in all-cause mortality than multiperson households. Interestingly, the effect appeared to be somewhat larger for owners of more active breeds like pointers and hunting dogs, possibly due to their need for greater physical activity.Of course, what we really care about is not whether dog ownership is associated with improved survival but whether dog ownership results in improved survival.9 Although empiricists justifiably have a bone to pick with people attempting to interpret association as causation, there are situations in which randomization is not available, feasible, or acceptable. In circumstances such as this, I ask myself 3 questions:Is the observed association real?Is the observed association likely to be causal?If the association is real and causal, what are the implications?Answering the first question is relatively straightforward. Since the association between dog ownership and improved survival has been replicated across multiple countries and in disparate populations (both the general population as well as individuals with preexisting cardiovascular disease), it is unlikely to simply be a chance finding. It is safe, then, to assume that the association is real. Answering the second question—ie, establishing whether the association is causal—is much harder. We must begin by examining whether there are unobserved confounders that may partially or entirely explain the observed association. At a population level, pet owners tend to be younger, wealthier, better educated, and more likely to be married, all of which improve cardiovascular outcomes. Owning a dog can be expensive, so individuals who own a dog may have higher disposable incomes than those who do not. High incomes are in turn associated with a lower prevalence of tobacco use, diabetes mellitus, and obesity in the population, so the observed relationship between pet ownership and outcomes may be partially due to socioeconomic factors and comorbidities. Finally, the association between dog ownership and good health may even be reverse causal because adults with excellent physical health are more likely to adopt a dog than those who are too ill or frail to care for a pet (though, at a population level, this is a smaller concern than socioeconomic confounders). In the Swedish studies, however, the association of dog ownership with lower mortality persists after adjustment for demographic and socioeconomic factors. In sensitivity analyses, additional adjustment for educational attainment and medication use do not appear to attenuate the observed association.It is certainly biologically plausible that dog ownership improves cardiovascular health (Figure). Several studies have shown that acquiring a dog perforce increases physical exercise (as anyone who has unsuccessfully tried to sleep past the time of a dog's routine morning walk can attest).10 Dog ownership may increase time spent outdoors, which has an independent positive effect on cardiovascular health.11 There may be salutary effects on physiological measures, such as lowering of systolic blood pressure and resting heart rates, and possibly small improvements in lipid profiles from the increased activity.12 Dog ownership may attenuate adverse hemodynamic responses to stress: in one randomized trial of pet adoption among hypertensive adults, a combination of pet ownership and ACE (angiotensin-converting enzyme)-inhibitor therapy attenuated stress-related blood pressure elevations better than ACE-inhibitor therapy alone.13 The company of dogs appears to have some benefit in critical illness: among hospitalized patients with advanced heart failure, a single 12-minute visit by a volunteer with a dog produced small but significant reductions in systolic pulmonary artery and pulmonary capillary wedge pressures, as well as in circulating levels of catecholamines.14 Exposure to the countless germs they bring into the home may favorably alter the gut microbiome of the owner, which in turn may alter cardiovascular outcomes. But the most salient benefits of dog ownership on cardiovascular outcomes are likely mediated through large and sustained improvements in mental health, including lower rates of depression, decreased loneliness, and increased self-esteem. This may explain why the effect appears to be larger for individuals living alone than those in multiperson households.Download figureDownload PowerPointFigure. Potential mechanisms for the cardiovascular benefit of dog ownership.Although outcomes researchers are perpetually hounded by concerns for residual confounding in nonrandomized studies, given the circumstances, we must triangulate our best estimate of effect size based on disparate data from diverse settings.9 Improved study designs may definitively answer this question in the future, but my interpretation of the collective evidence to date is that the association between dog ownership and improved survival is real, and is likely at least partially causal.That brings us to the third question. If we believe this association is real and causal, what are the implications? The findings of the 2 studies published here support the American Heart Association's position that dog ownership "may have some causal role in reducing cardiovascular disease risk (Level of Evidence: B)" and "may be reasonable for reduction in cardiovascular disease risk (Class IIb; Level of Evidence B)".12 The benefit appears to be additive to that of guideline-directed therapies and maybe greatest among individuals at highest risk (ie, those with established ischemic disease). But it is important to note that these studies only included individuals in high-income countries and in some cases oversampled native-born populations compared with immigrants. We should, therefore, exercise extreme caution in extrapolating these results to other populations. However, given the magnitude of the potential benefit—and likely little or no harm—these findings should encourage clinicians to discuss pet adoption with their patients, particularly those with preexisting cardiovascular disease and those living by themselves.But before leaping to the conclusion that increasing rates of dog ownership in the population will unleash enormous cardiovascular benefits, we should acknowledge that adopting a dog is a much larger undertaking than embarking on a new medical therapy. Adding a 4-legged member to the family involves long-term commitment and often substantial lifestyle changes. I concur with the American Heart Association's position that "pet adoption, rescue, or purchase should not be done for the primary purpose of reducing cardiovascular disease risk (Class III; Level of Evidence C)".12 Although a growing body of evidence now supports the idea that adopting a dog enhances the mental and physical well-being of its human companion, the real reward of dog ownership, in the words of Pulitzer Prize–winning poet Mary Oliver, is that there can hardly be a "sweeter arrangement" than the unconditional love of a loyal friend. The health benefits of dog ownership are a welcome and possibly substantial bonus.Little Dog's Rhapsody in the Night Mary Oliver' 1935–2019He puts his cheek against mineand makes small, expressive sounds.And when I'm awake, or awake enoughhe turns upside down, his four pawsin the airand his eyes dark and fervent."Tell me you love me," he says."Tell me again."Could there be a sweeter arrangement? Over and overhe gets to ask.I get to tell.From Dog Songs by Mary Oliver - Published by The Penguin Press New York Copyright © 2013 by Mary Oliver Reprinted by permission of The Charlotte Sheedy Literary Agency Inc.Copyright © 2013 by Mary OliverReprinted by permission of The Charlotte Sheedy Literary Agency Inc.AcknowledgmentsI would like to acknowledge Linda Valsdottir, Joanne Healy, and Gouri Dange, who provided editorial comments on a prior version of the article.DisclosuresNone.FootnotesThe opinions expressed in this article are not necessarily those of the editors or of the American Heart Association.Dhruv S. Kazi, MD, MSc, MS, 375 Longwood Ave, 4th Floor, Boston MA 02215. Email [email protected]harvard.eduReferences1. Vonholdt BM, Pollinger JP, Lohmueller KE, Han E, Parker HG, Quignon P, Degenhardt JD, Boyko AR, Earl DA, Auton A, Reynolds A, Bryc K, Brisbin A, Knowles JC, Mosher DS, Spady TC, Elkahloun A, Geffen E, Pilot M, Jedrzejewski W, Greco C, Randi E, Bannasch D, Wilton A, Shearman J, Musiani M, Cargill M, Jones PG, Qian Z, Huang W, Ding ZL, Zhang YP, Bustamante CD, Ostrander EA, Novembre J, Wayne RK. Genome-wide SNP and haplotype analyses reveal a rich history underlying dog domestication.Nature. 2010; 464:898–902. doi: 10.1038/nature08837CrossrefMedlineGoogle Scholar2. Irving-Pease EK, Ryan H, Jamieson A, Dimopoulos EA, Larson G, Frantz LA. Paleogenomics of animal domestication.Paleogenomics. Springer: Cham, Switzerland; 2018:225–272.CrossrefGoogle Scholar3. American Veterinary Medical Association. US Pet Ownership & Demographics Sourcebook.Available at: https://www.avma.org/News/JAVMANews/Pages/190115a.aspx. Accessed August 1, 2019.Google Scholar4. Lundqvist M, Carlsson P, Sjödahl R, Theodorsson E, Levin LÅ. Patient benefit of dog-assisted interventions in health care: a systematic review.BMC Complement Altern Med. 2017; 17:358. doi: 10.1186/s12906-017-1844-7CrossrefMedlineGoogle Scholar5. Ko HJ, Youn CH, Kim SH, Kim SY. Effect of pet insects on the psychological health of community-dwelling elderly people: a Single-Blinded, Randomized, Controlled Trial.Gerontology. 2016; 62:200–209. doi: 10.1159/000439129CrossrefMedlineGoogle Scholar6. Kramer CK, Mehmood S, Suen RS. Dog ownership and survival: a systematic review and meta-analysis.Circ Cardiovasc Qual Outcomes. 2019; 12:e005554. doi: 10.1161/CIRCOUTCOMES.119.005554LinkGoogle Scholar7. Mubanga M, Byberg L, Nowak C, Egenvall A, Magnusson PK, Ingelsson E, Fall T. Dog ownership and the risk of cardiovascular disease and death - a nationwide cohort study.Sci Rep. 2017; 7:15821. doi: 10.1038/s41598-017-16118-6CrossrefMedlineGoogle Scholar8. Mubanga M, Byberg L, Egenvall A, Ingelsson E, Fall T. Dog ownership and survival after a major cardiovascular event—a register-based prospective study.Circ Cardiovasc Qual Outcomes. 2019; 12:e005342. doi 10.1161/CIRCOUTCOMES.118.005342LinkGoogle Scholar9. Hernán M. The C-word: the more we discuss it, the less dirty it sounds.Am J Public Health. 2018; 108:625–626. doi: 10.2105/AJPH.2018.304392CrossrefMedlineGoogle Scholar10. Serpell J. Beneficial effects of pet ownership on some aspects of human health and behaviour.J R Soc Med. 1991; 84:717–720.CrossrefMedlineGoogle Scholar11. Twohig-Bennett C, Jones A. The health benefits of the great outdoors: a systematic review and meta-analysis of greenspace exposure and health outcomes.Environ Res. 2018; 166:628–637. doi: 10.1016/j.envres.2018.06.030CrossrefMedlineGoogle Scholar12. Levine GN, Allen K, Braun LT, Christian HE, Friedmann E, Taubert KA, Thomas SA, Wells DL, Lange RA; American Heart Association Council on Clinical Cardiology; Council on Cardiovascular and Stroke Nursing. Pet ownership and cardiovascular risk: a scientific statement from the American Heart Association.Circulation. 2013; 127:2353–2363. doi: 10.1161/CIR.0b013e31829201e1LinkGoogle Scholar13. Allen K, Shykoff BE, Izzo JL. Pet ownership, but not ace inhibitor therapy, blunts home blood pressure responses to mental stress.Hypertension. 2001; 38:815–820.LinkGoogle Scholar14. Cole KM, Gawlinski A, Steers N, Kotlerman J. Animal-assisted therapy in patients hospitalized with heart failure.Am J Crit Care. 2007; 16:575–585; quiz 586; discussion 587.CrossrefMedlineGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetailsCited By Surma S, Oparil S and Narkiewicz K (2022) Pet Ownership and the Risk of Arterial Hypertension and Cardiovascular Disease, Current Hypertension Reports, 10.1007/s11906-022-01191-8 Nallamothu B (2020) Hard Science, Circulation: Cardiovascular Quality and Outcomes, 10.1161/CIRCOUTCOMES.120.007359, 13:10, Online publication date: 1-Oct-2020. Bauman A, Owen K, Torske M, Ding D, Krokstad S and Stamatakis E (2020) Does Dog Ownership Really Prolong Survival?, Circulation: Cardiovascular Quality and Outcomes, 13:10, (e006907), Online publication date: 1-Oct-2020.Related articlesDog Ownership and Survival After a Major Cardiovascular EventMwenya Mubanga, et al. Circulation: Cardiovascular Quality and Outcomes. 2019;12Dog Ownership and SurvivalCaroline K. Kramer, et al. Circulation: Cardiovascular Quality and Outcomes. 2019;12 October 2019Vol 12, Issue 10 Advertisement Article InformationMetrics © 2019 American Heart Association, Inc.https://doi.org/10.1161/CIRCOUTCOMES.119.005887PMID: 31592727 Originally publishedOctober 8, 2019 KeywordsEditorialsriskdog ownershipcardiovascular diseasePDF download Advertisement SubjectsMortality/SurvivalQuality and Outcomes
Referência(s)