Determining use of preventive health care in Ontario

Differences by LHIN

Differences in the rates of use of preventive health care services by LHIN might have been affected by whether these services were available, especially in northern Ontario, where there are fewer physicians in practice, a high volume of patients per practice, and sparsely distributed medical centres.14,15 An important objective of any health care system is to provide equal access to health care or the opportunity for equal health outcomes. Programs targeted at specific geographic locations are needed to reduce regional disparities.

Differences by age

Influenza vaccination rates were highest among the elderly, which would be expected because influenza causes a great deal of morbidity and mortality among elderly people. Rates of mammography within 2 years were highest among those aged 65 to 74 and dropped substantially among those 75 and older, as 75 years is the suggested upper age limit for mammography screening.16 There is evidence that mammography screening of women 50 to 69 years old can reduce mortality from breast cancer by as much as 30%, although the benefits of mammography for those younger than 50 remain controversial.17,18 Rates of Pap smear use by age group were similar to rates in Canada as a whole. Greatest use of Pap smears (before adjusting for hysterectomy) occurs among those aged 25 to 34. Rates decline in each subsequent age group.19

Differences by socioeconomic status

Our findings indicate that those with higher incomes were more likely than those with lower incomes to have preventive screening for breast and cervical cancer. These results are consistent with those of previous studies that have shown that the higher a woman’s education or income level is, the more likely she is to receive mammograms and Pap tests.14,20–23

Despite access to universal health care in Canada, rates of use of preventive services still vary by socioeconomic status. This is the result of differences in knowledge, resources, and attitudes across socioeconomic levels. If the health care system is to be fully accessible, programs targeting specific groups need to be put in place to educate patients with lower socioeconomic status about the benefits of preventive health care.

With respect to influenza vaccination, our results showed that rates did not differ substantially by socioeconomic status, most likely a result of the universal vaccination plan targeting underserved populations that came into effect in 2001.24

Administrative versus survey data

Our results show that the rates obtained from the OHIP data were substantially lower than the rates obtained from the CCHS data for the same periods. This is consistent with results of previous studies with regard to the differences between self-reported and administrative data on use of preventive services.25–31 Since OHIP includes only fee-for-service claims, data on physicians and patients enrolled in alternative payment plans, such as those in place at Community Health Centres and Health Service Organizations, are excluded. This likely leads to an underestimation of the use of preventive services in Ontario.

Rates of influenza vaccination in the OHIP data might also be underestimated because of the approximately 35% of Ontario patients who do not receive vaccinations in doctor’s offices. Vaccinations are administered at workplaces, schools, and community-based clinics that are not monitored by OHIP.29 Creation of an immunization registry or assignment of a fee code for influenza vaccination would help to determine the rate of vaccination more accurately.

Ontario mammography screening rates determined from the OHIP administrative database also underestimate true rates as the data do not include screening offered by the Ontario Breast Screening Program. A study has shown that when Ontario Breast Screening Program and OHIP rates are combined, the rates become similar to CCHS rates.25 To obtain true rates of mammography screening, there needs to be harmonization between the Ontario Breast Screening Program and OHIP.

Low rates of Pap smear in the administrative database might be a result of billing or coding processes. For example, Pap tests performed during periodic health examinations might not be billed separately.28 A provincial cervical screening registry has been suggested to improve the accuracy of the data.27

Self-reported data might not give an accurate picture of use of preventive services. For example, one study showed that, while self-reported data were more accurate regarding whether a woman had had a mammogram, they were less accurate about when the woman had had it.26 Surveys are also susceptible to misunderstanding of terms or language in the questions. Privacy might also be an issue as patients might not wish to disclose certain information to interviewers. On the other hand, rates in the CCHS data might be overestimated because of respondents’ eagerness to report services as received in order to show good behaviour to the surveyor, when such services were not actually received.

Limitations

Both the self-reported data and the administrative data have their limitations. First, the CCHS relied on self-report and the voluntary participation of randomly selected participants; the results were not verified independently. Second, the CCHS did not try to determine the purpose of any screening tests. Third, the OHIP administrative data were not originally collected for the purposes of conducting health research. For example, the billing codes cited in physician claims have not been validated and, therefore, might not necessarily represent an accurate picture of preventive health care utilization.

Conclusion

Despite the limitations, our study contributes important information on the use of preventive health services in Ontario. There is room for improvement to increase the overall use of preventive health services as well as to develop programs to target specific geographic locations, socioeconomic classes, and high-risk groups. For example, research is needed to explore the barriers to receiving preventive health care from the perspectives of both patients and physicians. With the recent introduction of Canada’s human papillomavirus vaccination program, future research could also be conducted to determine the effectiveness of vaccination in reducing the prevalence of disease. There are obstacles to finding out what the true rates of preventive health care use are. We need to know what the criterion standard is for the delivery of such services to be able to move toward accurate measurement for reimbursement, to measure reduction in preventable illnesses, and to evaluate the effects of preventive health programs.