PBRs: Purpose and rationale

The first step in planning a registry is the formulation of a clearly defined purpose and rationale; this makes easier to evaluate whether the registry is the right approach to obtain the data of interest [9, 10]. A defined purpose helps to clarify the data needed. Attempts to produce an all-inclusive registry may add cost but not value, resulting in an overly data collection that reduces quality and completeness. The value of a registry must be examined at intervals to ensure that the objectives are still relevant and are met. If the registry has several purposes, these should be translated into specific objectives [11]. This process needs to take into account the interests of researcher, stakeholders, and policy makers. Clear objectives are essential to define data collection and to ensure that the registry addresses the important issues (http://www.cuore.iss.it/eng/bridge/pdf/WP8-D8.2_Population based registries_2017-10-30.pdf).

The first experience of a population-based registry in the field of CVD was the WHO Myocardial Infarction Community Registers in 1967 [12]; it was implemented by a group of experts convened by the WHO Regional office for Europe to (a) evaluate the extent of acute myocardial infarction (AMI) in the community; (b) monitor the effect of changes in the management of AMI and different types of intervention; (c) provide an assessment of the validity of mortality statistics; (d) select a pool of patients who could be studied in detail and focus attention on specific problem areas. In order to obtain a statistically sufficient number of notifications, it was decided that the duration of the registration should cover one year with a 12 months follow-up after the heart attack; each community had to be well defined demographically as census data were indispensable for establishing incidence. All persons in whom there was “any suspicion” that AMI (on the basis of history, electrocardiogram (ECG), enzyme and post mortem results) might have occurred in population who were ≤ 65 years old at the onset of the acute attack and who were resident in the registration area were admitted to the registry. The cut-off point of 65 years was chosen in order to keep the registry to a size that was easy to handle and to exclude older patients with multiple pathologies. The registry examined the incidence of AMI and the influence of smoking, obesity and hypertension on AMI to show which people in the community were specifically at risk.

The WHO Myocardial Infarction Community Registers were followed by the WHO MONICA Project (MONItoring Trends and Determinants in CArdiovascular Disease) [13] which was designed to answer key questions arising from the 1978 Bethesda Conference on the Decline in Coronary Heart Disease Mortality: ‘are reported declines in coronary heart disease mortality genuine? If they are, how much is attributable to improved survival rather than to declining coronary-event rates? Are these trends related to changes in risk factors and health care?’ [13]. It was a very wide project conducted between the half of ‘80s and the half of ‘90s overall the world that allowed, for the first time, (a) to collect and register, during 10-year surveillance of 37 populations in 21 countries, 166,000 first and recurrent events in men and women aged 35-64 years; (b) to classify, following the same standardised diagnostic criteria (site and duration of pain, evolution of ECG findings, variation of cardiac enzyme values and history of Ischaemic Heart Disease (IHD), and, if performed, necropsy), all suspected events in fatal and non-fatal ‘definite’, ‘possible’, ‘ischemic cardiac arrest with successful resuscitation’, and ‘insufficient data’ events. An important improvement in the use of standardised diagnostic criteria was the introduction of a quantitative ECG coding system, the Minnesota Code [14]. Main results of the WHO MONICA Registry demonstrated that contributions to changing of IHD mortality varied, but in populations in which mortality decreased, coronary event rates contributed for two thirds and case fatality for one-third [2]. These trends were related to changes in known risk factors (systolic blood pressure, total cholesterol, smoking habit and body mass index) daily living habits, health care and major socio-economic features measured at the same time in defined communities in different countries [13].

The European Cardiovascular Indicators Surveillance Set (EUROCISS) Project was launched in 2000 by a partnership of 14 EU countries; many of the partners were collaborating centres of the MONICA Registry and had actively continued the registration of cardiovascular events. The aim of the project was, starting from the MONICA experience, to develop health indicators and recommendations for monitoring the distribution and impact of CVD in Europe in order to facilitate cross-country comparisons and improve CVD prevention. An updated picture of the existing population-based registries of AMI and stroke in Europe was published, with a detailed description of sources of information, data collection, validation methods and indicators assessed in the different population-based registries [15]. Even though deriving from the MONICA experience, these registries basically were not comparable since they collected and validated events with different characteristics (population size, age-range under surveillance, International Classification of Diseases-ICD codes used to identify suspected events, validation procedures) [15]. AMI incidence/attack rate, case fatality and prevalence were suggested for inclusion in the European Community Health Indicators (ECHI) short list (n.24 and 25) [16]. A second phase of the EUROCISS Project (2004–2007) was launched aiming at (a) developing knowledge, tools and expertise among Member States for CVD surveillance and prevention; (b) preparing the Manual of Operations for the implementation of a population-based registry of AMI/acute coronary syndrome (AMI/ACS) [17], of stroke [18], and of CVD surveys for assessing standardized indicators (prevalence of old myocardial infarction, heart failure, late effects of cerebrovascular diseases, and other CVD), and for identifying a minimum set of questions and exams to be included in the Health Examination Survey (HES) for evaluating the prevalence of CVD at European level [19]. The EUROCISS project provided recommendations to assess reliable and comparable indicators, methodologies for validating suspected cases and for classifying events, and suggested a stepwise procedure to assess the indicators proposed and recommended for the ECHI list.

At national level, a pilot study for the population-based Italian Registry of CVD was implemented covering fatal and non-fatal coronary and cerebrovascular events in the general population aged 35–74 years. It was launched in Italy on 2000 following the MONICA and EUROCISS experiences with the aim of estimating periodically attack rates and case fatality rates of coronary and cerebrovascular events in geographical macro-areas representative of the country, in order to monitor time trends of CVD of major impact in adult population and assess the geographical gradient North-South [20, 21]. Some questions to which the pilot study for the population-based Italian Registry of coronary an cerebrovascular events intended to answer included, for example: – what is the frequency of AMI and who are the persons at particular risk?; − are there any difference in the incidence of AMI between North and South of Italy?; − what proportion of people suffering from AMI recovers satisfactorily and what proportion dies?; − where does that occur, at home or in a hospital?; − what happens to patient after leaving hospital?