This study is the first to comprehensively evaluate the benefits of regular primary care for the secondary prevention of ischaemic heart disease in older patients at the population level. The results suggest that a relatively small increase in regularity between GP visits is required in order to protect against all-cause mortality, ischaemic heart disease mortality and repeat ischaemic heart disease emergency hospitalisations in patients aged over 65 years with a history of hospitalisation for ischaemic heart disease.
Using whole-population, routinely-collected, administrative medical/health data was a strength of this study as it minimised recall bias and loss-to-follow-up. We felt confident in using WA hospital data for patient ascertainment as the WA Department of Health conducts quality audits of the ICD coding of hospital morbidity from hospital charts on a regular basis and a validation study found the accuracy of heart failure coding from this data to be exceptionally high34
. Furthermore, all but a very small number of state-funded GPs in WA qualify for government subsidy support and it is thus unlikely that any of the patients in our study had GP visits that we missed.
Despite the number of strengths, a few limitations warrant attention. Firstly, reverse causation (protopathic) bias can occur in health services research when the increased frequency of the health care services immediately prior to a disease outcome creates a misleading association between the two factors32
. We attempted to minimise this problem by implementing a six months wash-out period between the exposure and follow-up periods, where no exposure or outcomes were ascertained. A wash-out period of this length has been shown in similar research to adequately account for this type of bias31
. Secondly, the severity of the initial ischaemic heart disease hospitalisation may affect the inclination of a patient to seek regular primary care once discharged from hospital. We explored adjusting all our analyses for proxy measurements of intial ischaemic heart disease severity such as: admission type at first ischaemic heart disease hospitalisation (emergency/non-emergency); concurrent acute myocardial infarction at first ischaemic heart disease hospitalisation; length of first ischaemic heart disease hospital stay; and revascularisation procedure at first ischaemic heart disease hospitalisation. None of these adjustments had any significant effect on the associations or risk estimates demonstrated in the study and we therefore excluded these variables from the Cox regression models. Thirdly, a large part of our participants died or were re-hospitalized prior to commencement of follow-up and could thus not be included in the analysis. This may have been a cause for a concern regarding the efficacy of regular GP visits. However, the people who were included in the analysis were more likely to have regular GP visits, indicating that regular GP visits point towards better health and longevity. Lastly, using this type of data did create some limitations with respect to information availability as we were unable to assess continuity of care. This was due to the fact that we did not have information on whether the patients saw the same GP at each visit.
Evidence exists indicating that hospitalisation for a number of chronic health conditions could be preventable with sufficient primary care35
. These conditions are known as Ambulatory Care Sensitive Conditions (ACSCs) and include, as an example, diabetes, respiratory diseases, various cardiovascular diagnoses, and convulsive disorders36
. The protective effect of GP accessibility and the pattern of GP contact against potentially preventable hospital admissions and adverse health events has been supported by several previous studies35,37–41
. As an example, high primary care physician density appears to protect against potentially preventable hospital admissions35
, whereas lack of a primary care physician38
, fewer physician visits39
, living in primary medical care shortage areas40
, and lack of access to primary care41
appear to lead to increase in preventable hospitalisations. Also, delayed access to health care has been found to increase the risk of mortality in veterans42
Our results support the findings from an Irish intervention study where ischaemic heart disease patients visited their primary care physician up to four times annually19
. The authors reported improvements in blood pressure, cholesterol levels, and smoking status despite the fact that no special interventions on diet or physical activity were implemented for the patients19
. Rather, GPs only provided advice/encouragement on healthy eating and physical exercise in addition to taking physical and medical measurements19
. Hence, simply visiting a GP regularly appears to play a significant role in the prevention of deteriorating cardiovascular health. In our study, we used a new measure for regularity previously developed by our group22,23
that specifically measured regularity between GP visits per se, and found that visiting a GP regularly appears to protect against morbidity and mortality in ischaemic heart disease patients. The results suggested that only relatively small increase in regularity is required in order to be protective and that when this threshold is reached, only a small additional benefit of increased regular GP attendance is apparent. The fact that regular primary care seems protective is an important finding considering that the literature consistently reports sub-optimal compliance with recommended secondary prevention strategies despite a plethora of evidence showing the importance of such strategies. For example, a recent systematic review concluded that pre-planned community pharmacist or nurse consultations, patient education and structured monitoring of medication and risk factors improved total cholesterol levels in patients with ischaemic heart disease11
. Also, clinical trial evidence consistently supports the efficacy of pharmacotherapies in reducing cardiovascular morbidity and mortality12,13
and rehabilitation programs have been shown to play a pivotal role in treatment and management of ischaemic heart disease patients43–45
. As a result, clinical guidelines commonly suggest that all patients with ischaemic heart disease should participate in at least some form of a secondary prevention program46
Despite the ability of current preventive strategies to reduce cardiovascular morbidity and mortality, compliance remains poor12–14
. Some of the reasons for poor compliance include older age, lower socio-economic status, lack of motivation, transport difficulties, limited availability of preventive programs, and financial constraints17,18
. One feature of The Chronic Care Model20
—which focuses on proactive, planned care—includes automated reminder systems to support regular care. If put in place, such systems could make a great contribution towards increasing compliance rates. Furthermore, the vast majority of Australians over 65 years of age are eligible to receive a government concession card, entitling them to visit a GP regularly at low or no out-of-pocket expense. As a result, regular appointments with GPs are a financially feasible way for older patients to manage and monitor their disease, at least in the Australian setting.
Regular appointments with a GP as a form of secondary prevention for ischaemic heart disease reflect a more proactive approach to disease management. They create time to review the secondary prevention strategies in place, such as medication therapy, and may contribute towards medication adherence and early detection of adverse disease symptoms. In addition, regular GP appointments may help reduce stress and anxiety experienced by the patient. Evidence suggests that the reduction of emotional stress is an important consequence of secondary prevention47
. Hence, any psychosocial support provided by the GP is likely to contribute towards reduction in future coronary risk.
Another possible mechanism for the positive effect of regular primary care is the long-term maintenance of a healthy lifestyle. Patients with a recently diagnosed ischaemic heart disease tend to begin a new healthy lifestyle with good intentions. However, the maintenance of a healthy lifestyle depends on long-term advice and personal involvement in secondary prevention48
. As such, having regular appointments with a GP may increase the motivation of ischaemic heart disease patients to comply with secondary prevention strategies and stay on track with a healthy lifestyle. Such commitment will then in turn reduce their risk of mortality and morbidity in the long-term49