The study involved a multicentered cross-sectional survey, the Primary Care Organizations Reciprocal Evaluation Survey Study (PROGRESS) 2018. The PROGRESS was conducted by a practice-based research network in Japanese primary care. This study was approved by the Research Ethics Committee of Kyoto University, Japan (approval number R1342).
The PROGRESS is a biannual cross-sectional survey to improve quality of care. The survey has collected data regarding PX, health-related quality of life, health conditions, healthcare utilization, clinical process, and sociodemographic characteristics in adult outpatients in Japanese primary care settings since 2015. The 25 participating institutions are distributed throughout both urban and rural areas (Kanto, Tyubu, Hokuriku, Kinki, and Kyusyu; Supplemental Appendix 1). These institutions include 19 clinics and 6 hospitals with fewer than 200 beds. We included the small- and medium-sized hospitals into the study because, in Japan, primary care has been offered not only in a clinic but also in a small hospital.27 A self-completion questionnaire was distributed to all outpatients aged 20 years and older who visited one of the participating institutions within the 1-week survey period between February and March 2018. The surveys were delivered by a receptionist in each participating institution. The participants completed the anonymous survey, put it into envelope, and posted it into the collection box in each institution by themselves. The ethical committee at the Kyoto University Graduate School of Medicine provided ethical approval for the study (approval number: R1342).
All patients aged ≥ 65 years who participated in the PROGRESS 2018 were included in the study.
Patients without usual source of care and patients who have usual source of care other than the participating institutions were excluded from the study. This was because JPCAT is a questionnaire to assess patient experience of a patient who has usual source of care, and this study aims to investigate the association between patient experience of a patient who has usual source of care and vaccination status. Patients’ usual sources of care were recorded via three questionnaire items, and the algorithms used in the Japanese version of the Primary Care Assessment Tool (JPCAT)28 were identical to those used in the original Primary Care Assessment Tool Adult Expanded Edition, as follows16: (1) Is there a doctor that you usually go if you are sick or need advice about your health?; (2) Is there a doctor that knows you best as a person?; and (3) Is there a doctor that is most responsible for your health care? Patients were considered to have a usual source of care if they answered any of the three questions positively.
All variables were evaluated using a self- administered questionnaire.
Primary Outcomes: Influenza and Pneumococcal Vaccine Uptake
The following two items were used to explore vaccination status: “have you received an influenza vaccination within the past year?” and “have you ever received a pneumococcal vaccination?” The reason for the inclusion of these items was that the CDC recommended annual influenza and pneumococcal vaccinations for older adults.3 We omitted shingles and tetanus vaccination because these vaccinations have not been included into routine vaccination in Japan.29
Explanatory Variable: PX in Primary Care
We used the JPCAT28 to measure PX in primary care. The JPCAT, based on the Primary Care Assessment Tool Adult Expanded Edition,16 was developed using the Delphi method, cognitive testing, and a validation study to establish its applicability to the Japanese healthcare system. The 29-item tool includes six multi-item subscales representing five primary care attributes including first contact, longitudinality, coordination, comprehensiveness, and community orientation.30 We employed total score of the JPCAT as main exposure and score of each domain as secondary exposure. The analysis for the secondary exposure was exploratory analysis. The brief description of each domain is the following:
First contact: The care is first sought from the primary care provider when a new health or medical needs arises. The services must be accessible and used by the population each time a new need or problem arises. The JPCAT mainly assesses PX regarding out-of-hours care in primary care setting.
Longitudinality: This refers to the longitudinal use of a regular source of care over time, regardless of the presence or absence of disease or injury. The JPCAT mainly assesses whether the patient feels that their primary care physician recognizes them as a whole person.
Coordination: The essence of coordination is “the availability of information about prior and existing problems and services, and the recognition of that information as it bears on needs for current care.” The JPCAT mainly assesses PX regarding referral to the specialist in the past.
Comprehensiveness (services available): This refers to the availability of a wide range of services in primary care and their appropriate provision across the entire spectrum of types of needs for all but the most uncommon problems in the population by a primary care provider. In the “services available,” the JPCAT mainly assesses whether the patient feels that the patient can receive care for mental health, dementia, and advanced care planning if necessary.
Comprehensiveness (services provided): In the “service provided,” the JPCAT mainly assesses PX regarding appropriate advice about daily habits in the past.
Community orientation: This refers to care that is delivered in the context of the community. The JPCAT mainly assesses PX regarding home visits and whether the patient feels that their primary care physician is interested in not only individual health problems but also the problems in the community.
Details of the content of the JPCAT are available in Supplemental Appendix 2.
The JPCAT scoring system is structured as follows: responses are provided using a 5-point Likert scale ranging from 0 to 4. The mean item scores in each domain are multiplied by 25 to yield domain scores ranging from 0 to 100, with higher scores indicating better PX. The total score is calculated as the mean score for the six domains and reflects the overall quality of core primary care attributes. The JPCAT has demonstrated good reliability and validity.28 A difference of 3 points or more in the JPCAT is regarded as clinically meaningful in magnitude.31,32,33,34
We included age, sex, years of education, annual household income, and self-related health as covariates because of their known associations with vaccine uptake and PX. PX is associated with age, sex, socioeconomic status, income, education, and self-rated health.35,36,37,38 Vaccine uptake can also be affected by age, socioeconomic status, and self-rated health.8, 39, 40
To determine whether vaccination uptake was associated with JPCAT total scores, we used a generalized linear mixed-effects model (random intercept model) that included random effects for institution and covariates (age, sex, years of education, annual household income, and self-rated health) as fixed effects. The model incorporated the random intercept for institutions, using centering within the cluster. To allow for uncertainty in the missing values for independent and dependent variables, we used multiple imputations by fully conditional specification, which included JPCAT scores, age, sex, years of education, annual household income, self-rated health, and vaccination status. We calculated 95% confidence intervals using robust standard errors. The statistical analysis was performed using R version 3.4.3 (R Foundation for Statistical Computing, Vienna, Austria; https://www.r-project.org).