Our study found that guideline-recommended medications for MI secondary prevention were prescribed more often in period II than in period I but there are significant differences among age and gender subgroups. BBs are still prescribed in smaller dosages than recommended in guidelines. In addition, we found that during the past 13 years the mean age of MI patients has increased but the 30-day and 1-year mortality of MI patients in Estonia decreased significantly.
A positive shift has taken place in prescribing guideline recommended MI secondary prevention medications in Estonia, but our patients’ rate of adherence is still lower than in several studies conducted elsewhere in Europe. The EUROASPIRE V study (3) looking into secondary prevention practices in 27 European countries reported 81 % of patients receiving BBs, 75 % receiving ACEis or ARBs and 80% receiving statins after > 6 months from MI. 93 % of patients received anti-platelets in EUROASPIRE V, but aspirin, besides P2Y12 inhibitors, was also counted for. It is of importance, that only patients < 80 years of age were included in EUROASPIRE V and data was derived from patient interviews. Gross et al (9) also reported high adherence to MI secondary prevention medications in an intervention program with regular visits to office-based cardiologist in Germany, proving that in a selected group of highly motivated patients who are willing to participate in high intensity secondary prevention programs, good results are achievable. But in every day practice, as did also our data show, on unselected patient populations the results are far from ideal with moderate rates of adherence also reported by Huber et al. in Switzerland (10).
In our study an unselected population of MI patients was observed, and it was evident that women and the elderly (patients in > 80 years age group) were considerably less likely to receive statins and P2Y12 inhibitors. Saar et al. (11) showed that in Estonia, elderly patients, who comprise nearly 80 % of the GRACE score high risk population, undergo percutaneous coronary intervention (PCI) and use P2Y12 inhibitors significantly less often during hospitalization. Also, a correlation between performing PCI and use of P2Y12 inhibitors in other age groups was demonstrated.
In addition, we found that the triple combination of BBs, ACEis/ARBs and statins was significantly less often prescribed to women and the elderly. Again, these findings correlate to other studies on unselected population (10) and could partly explain lower rates of adherence in our study compared to results from selected patient populations.
It is common practice that physicians are cautious when prescribing secondary prevention medications to elderly patients with the concerns of possible adverse effects, drug-drug interactions and questionable benefit in mind (15–17). Recently evidence has shown that elderly patients do benefit from guideline recommended secondary prevention drug therapy after MI without any substantial additional harm (18–21).
Also, the fact that women use less guideline recommended MI secondary prevention drug treatment is a recognized phenomenon though the reasons behind it are not well known (16, 22–23).
Rate of prescribing BBs has increased significantly over time in Estonia. However, regardless of sex and age, beta blocking agents were used in relatively small dosages – an issue also evident in 2004. It is a universally recognized problem which still is not very well explained (12). At one hand, the length of hospital stay is increasingly shortening and follow up visits are infrequent which discourage general practitioners from up titrating the initial dose. On the other hand, evidence form research has risen the question of appropriateness of the guideline recommended doses (13) and indication of BBs in the PCI, antiplatelet and statin era (14).
The number of patients to whom no secondary prevention medications were prescribed, had risen from 5.6 % in period I to 8.3 % in period II. The majority of these patients were in the > 60 years age groups, for 42.4 % of these patients no coronary angiography was performed. 18.5 % of them died during the follow up in the period II cohort. No description for the period I cohort was available. The reasons for this slight negative tendency can only be assumed (e.g., more patients survive out of hospital cardiac arrest who remain with a profound cognitive deficit and are managed in nursing homes, some patients leave the country etc.) and need to be investigated further.
In Estonia, the CV disease mortality rate is declining. The MI in hospital management has improved considerably (15) as can be concluded from the decreased 30-day mortality rate. But as the number of diabetics and overweight patients, often already in younger age groups, and octogenarians is increasing, solutions for achieving and maintaining MI secondary prevention guideline recommended goals (including high adherence to medical therapy), are needed (16).
Strengths and limitations
The major strength of this study is the characteristics of the data – full representation of the MI patients’ population without a selection bias. Also, information is available without interviewer bias or recall bias.
Our study has certain limitations. Firstly, the defined daily dosages methodology used is not the most accurate and probably overestimates adherence slightly. It was chosen, instead of medication possession rate methodology, to enable comparison with the previously conducted study using the DDD methodology. By using this methodology, we cannot differentiate everyday-users from short-time-users of certain drug.
Secondly, there is no data available to confirm whether the patients actually take the purchased medications. So, the actual usage is probably lower than the presented results. But still, accounting reimbursed prescriptions as used medications by patient is a validated methodology (17).
Thirdly, we do not have any information to explain the reasons behind nonadherence nor for not finding any prescriptions in the database for some patients.
Fourthly, we have no data about contraindications or information about intolerance of recommended dosages regarding individual patients which may explain some of the nonadherence to guidelines.