Study population and setting
This was a cross-sectional study using self-administered questionnaires among pet owners and veterinarians. The questionnaires were distributed to owners who visited a veterinary clinic in Tokyo between July 5–7 and July 9–11 in 2021. This veterinary clinic is a relatively large private clinic in an area of the Tokyo metropolitan district whose residents have average-level incomes. The clinic receives referral cases from surrounding clinics. There are approximately 15 veterinarians working at the clinic, who only treat cats and dogs and consult in all specialties.
The first author, a veterinarian who had been working at this clinic, carried out participant recruitment and distribution of the questionnaires. All veterinarians working at the clinic were asked to participate in the survey and to sign a consent form. The questionnaires were distributed to owners who met either of the following two criteria: 1) completed a consultation where the veterinarian considered that a new decision had been made (as reported by the veterinarian), and 2) completed a consultation where a new medication was prescribed or a new treatment was provided (confirmed by the medical record). If the consultation met either of these criteria, the owner was recruited to participate in the study after the consultation was completed; owners were asked to sign a consent form and complete a questionnaire. A questionnaire was also distributed to the corresponding veterinarian who examined each pet whose owner participated in the survey. A veterinarian completed a questionnaire for each consultation included in the study. Consent forms and questionnaires were collected on the same day. Study participation and survey completion were on a voluntary basis. Participants were informed that they could withdraw from the study at any time, and owners were assured that their veterinarian would not be informed of their individual responses. No pilot study of this research has been conducted.
The following variables pertaining to pet owners and veterinarians were obtained using the questionnaire.
Decision-making preferences were measured with an item used in previous studies on cancer care [34, 35]. We replaced the term “doctor” in the original item with “veterinarian”. Pet owners were asked if they prefer 1) the veterinarian to make the treatment decision on their own, 2) the veterinarian to make the treatment decision after talking them, 3) to make the treatment decision together with the veterinarian, 4) to make the treatment decision after hearing the veterinarian’s opinion, or 5) to make the treatment decision on their own.
According to the previous study, 1) and 2) were categorized as “passive,” 3) as “shared,” and 4) and 5) as “active” decision-making in the analyses .
The implementation of SDM was measured using the Shared Decision Making Questionnaire for pet owners (SDM-Q-9) and the version for veterinarians (SDM-Q-Doc). Because some consultations may not involve any new decision-making (i.e., routine subcutaneous transfusion or only prescription of medications), we asked participants to complete the questionnaire only if there was new decision-making during the consultation.
Both the SDM-Q-9 and SDM-Q-Doc have a one-factor structure that consists of nine items; this structure measures the concept of SDM from the patient’s (SDM-Q-9) and the physician’s (SDM-Q-Doc) perspective. All nine items of both the SDM-Q-9 and SDM-Q-Doc are rated on a six-point Likert-type scale ranging, from 0 (Not applicable at all) to 5 (Very applicable). Total scores on each scale range from 0 to 45, with higher scores indicating a higher level of SDM. We followed the development procedure of the original version and transformed the sum scale to range from 0 to 100 points.
As of 2022, both questionnaires have been translated into 29 languages and their validity and reliability have been confirmed in various cultures and languages [36,37,38,39,40]. The Japanese version of the SDM-Q-9 has been shown to be reliable and valid . The SDM-Q-9 and SDM-Q-Doc are also available in various versions for adaptation to other health care professionals and pediatric parents [41, 42]. The SDM-Q-9 and SDM-Q-Doc have been applied in veterinary medicine by Testoni et al. [33, 36]. Permission to change the terms “doctor” to “veterinarian” and “patient” to “pet owner” to fit the veterinary context in translation of the questionnaire was obtained from the authors of the original study (January 27, 2021).
Satisfaction with consultation
We used a scale from a study that investigated the satisfaction level of outpatients in Japan , replacing the term “doctor” with “veterinarian.” The scale consists of four items addressing patient satisfaction with the consultation, which are rated on a five-point Likert-type scale ranging from 1 (Not applicable at all) to 5 (Very applicable). Total scores on each scale ranged from 4 to 20, with higher scores indicating greater satisfaction.
Characteristics of survey respondents
The following variables were obtained as part of the questionnaire for pet owners: the owner's sex, age, education level, living situation, other animal ownership. We also queried their pet’s species, sex, age, health insurance status, and number of previous consultations.
The following variables were obtained as part of the questionnaire for veterinarians: sex, age, and years of clinical experience.
In human medical care, the correlation coefficients of previous studies that examined the correlation between the SDM-Q-9 and consultation satisfaction ranged from 0.28 to 0.39 .
Assuming a correlation coefficient of 0.35 in veterinary medicine, with α = 0.05 (two-sided) and power = 0.9 (β = 0.1), the sample size is 82; with α = 0.05 (two-sided) and power = 0.8 (β = 0.2), the sample size is 67. The sample size was calculated using SAS version 9.4 (SAS Institute Inc., Cary, NC, USA).
Descriptive statistics were used for responses on the SDM-Q-9, SDM-Q-Doc and for pet owners' satisfaction as adapted veterinary medicine. Distributions were confirmed using the Shapiro–Wilk test.
Pearson's or Spearman's correlation coefficients were calculated for the association between SDM-Q-9 and SDM-Q-Doc, SDM-Q-9 and pet owners' satisfaction, and SDM-Q-Doc and pet owners' satisfaction. We used Spearman's correlation coefficient when scores were considered non-normally distributed according to the Shapiro–Wilk test.
The relationships among pet owners’ characteristics, decision-making preferences, responses on the SDM-Q-9 and SDM-Q-Doc, and pet owner’s satisfaction were analyzed using the Wilcoxon rank-sum test (for comparisons between two groups) or Kruskal–Wallis test (for comparisons between more than two groups). To identify factors strongly associated with satisfaction, variable selection was carried out using a stepwise method in a linear regression model, with pet owners’ satisfaction as the response variable and sex, age, education, life circumstances, owning other dogs or cats, number of consultations, and characteristics of pets as explanatory variables.
The following analyses were also performed as sensitivity analyses. The correlation between the veterinarian SDM scores and pet owner satisfaction (or owner SDM scores) was analyzed using a two-step approach considering clustering of SDM scores for veterinarians because the correlation coefficient does not account for similar responses from the same veterinarian. Slopes were estimated using a simple regression with each veterinarian SDM score as a response variable and pet owner satisfaction (or owner SDM score) as an explanatory variable, followed by the Z-test with a null hypothesis of the mean slope being zero.
The statistical significance for all tests was defined as p < 0.05. All analyses were performed using SAS version 9.4.
The Teikyo University Ethical Review Board for Medical and Health Research Involving Human Subjects approved this study after ethical review (approval No. 21–001). All procedures performed in studies involving human participants were conducted according to the ethical standards of the institution and those of the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards.