Association between pet ownership and physical activity levels, atopic conditions, and mental health in Singapore: a propensity score-matched analysis

Although existing literature increasingly suggests a positive influence of pet ownership on human physical activity levels, results from many European, American, and Japanese studies have been inconsistent. How pet ownership impacts mental health and atopy is likewise controversial and whether distinct demographic subgroups experience differential effects is unclear. This cross-sectional study surveyed participants (n = 823) via a self-administered online questionnaire. Comparisons of outcomes between pet owners and non-pet owners with subgroup analyses were performed within a propensity score-matched subset (n = 566) of respondents. There were no differences in physical activity levels or mental health scores between pet owners and non-pet owners. In subgroup analyses, compared to non-pet owners, main pet caregivers reported 14.1 (95% CI 2.79–25.3) and 19.0 (95% CI 4.70–33.3) more minutes per week of moderate- and vigorous-intensity physical activity respectively and higher SF-36 emotional well-being (β = 2.7, 95% CI 0.100–5.32) and energy scores (β = 3.8, 95% CI 0.410–7.27). Age was a significant effect modifier of the association between pet ownership and emotional well-being, energy and social functioning scores, with greater scores above the ages of 39, 35 and 39 years old respectively (interaction p = 0.043, 0.044, 0.042). Finally, pet acquisition was associated with worsening of allergic rhinitis, while pet ownership cessation was associated with improvement of allergic rhinitis and eczema symptoms. To our knowledge, this is the first study addressing the public health impact of pet ownership in Southeast Asia and its findings add contextual nuance to suggest potential benefits derived from pet ownership.

1 Yong Loo Lin School of Medicine, National University of Singapore and National University Health System, Singapore 2 Saw Swee Hock School of Public Health, National University of Singapore and National University Health System, Singapore 3 Centre for Infectious Disease Epidemiology and Research, National University of Singapore, Singapore *Correspondence: Junxiong Pang, MSc, PhD; Saw Swee Hock School of Public Health, National University of Singapore, 12 Science Drive 2, Level 10, Singapore 117549, Republic of Singapore; E-mail: ephpjv@nus.edu.sg

Eligibility Criteria (in English)
Inclusion Criteria: • Adults from 21 to 64 years of age residing in Singapore for the last 6 months.
• Participants may be clients of licensed veterinary clinics, who are petowners/caregivers of the above-mentioned pets.

Exclusion Criteria:
• Legal minors under the age of 21 years.
• Adults aged 65 years and above.
• People who own therapy or guide dogs.
• People with physical disabilities, defined as requiring assistance in at least 1 activity of daily living (ADLs): dressing, eating, ambulating, transferring, toileting, maintaining hygiene.

Questionnaire (in English)
Screening questions before questionnaire 1. I am between 21 and 64 years of age (inclusive) and am willing to participate in this study. 88. Compared to before you had your pet, how has your mood changed?
☐ 5. Much better now than before ☐ 4. Somewhat better now than before ☐ 3. About the same ☐ 2. Somewhat worse now than before ☐ 1. Much worse now than before Section Header: Physical activity [6,7] 89. How many days per week do you engage in mild-intensity physical activity?     Section Header: Breathing, nose, eye and skin conditions [8,9] 105. In your entire life, have you had any wheezing or whistling in your chest? Propensity-score distribution after 1:1 matching Supplementary Figure S1. Propensity-score model and matching diagnostics. Propensity-scores (i.e., conditional probability of pet ownership) were estimated using logistic regression modelling of baseline demographics and other relevant covariates, and showed good calibration and discrimination. Propensity-scores between pet-owners vs non-pet-owners were well-balanced after 1:1 greedy matching using a caliper of 0.25 * standard deviation of the linear predictor (i.e., logit).  Lukaschek, K., Vanajan, A., Johar, H., Weiland, N., & Ladwig, K.-H. (2017). "In the mood for ageing": determinants of subjective well-being in older men and women of the population-based KORA-Age study. BMC Geriatrics, 17 (1). doi: 10.1186/s12877-017-0513-5 M3 Lifetime prevalence of MDD was significantly higher among the Indians than the Chinese and Malays Chong, S. A., Vaingankar, J., Abdin, E., & Subramaniam, M. (2012). The prevalence and impact of major depressive disorder among Chinese, Malays and Indians in an Asian multi-racial population. Journal of Affective Disorders, 138 (1-2), 128-136. doi: 10.1016/j.jad.2011.11.038 Indians exhibited higher rates of depression as compared to chinese and Malays. Minority groups are known to experience higher anxiety and depression rates due to multiple stressors. Ganasegeran, K., Renganathan, P., Manaf, R. A., & Al-Dubai, S. A. R. (2014). Factors associated with anxiety and depression among type 2 diabetes outpatients in Malaysia: a descriptive cross-sectional single-centre study. BMJ Open,4(4). doi: 10.1136/bmjopen-2014-004794 M4 Decline in mental health for men who were separated or widowed, as compared to men who remained married. Similar declines in mental health were found for women who separated or became widowed.

Marriage
Pet attachment score > 4 Supplementary Figure S2. Propensity-score-matched comparison of weekly physical activity levels between pet-owners vs non-pet-owners in the full matched set as well as selected subgroups. Subgroup-specific effects were computed as marginal contrasts by specifying a full factorial interaction between pet ownership and the relevant covariate.  Subgroup-specific effects were computed as marginal contrasts by specifying a full factorial interaction between pet ownership and the relevant covariate.