1. Data sources for pharmacoepidemiological research
1.1. Primary data
1. Surveys
A survey is the collection of data on knowledge, attitudes, behaviour, practices, opinions, beliefs or feelings of selected groups of individuals, by asking them in person, on paper, by phone or online. They generally have a cross-sectional design, but repeated measures over time may apply for trends assessment. If, for example, the information about specific medication-taking behaviour is required, the participant in a study that uses primary data collection can be asked. This information would most likely not be obtained through secondary data from prescription records provided by a pharmacy or routine data collections.
Survey limitations may be low response rates, allowing for possible bias. The response rate should therefore be reported in a standardised way in surveys to allow comparisons. The increasing use of online surveys requires that survey methods are adapted but should not sacrifice representativeness by accessing only populations which visit these websites (avoid bias). Similarly, the increasing use of health care professional and patient panels needs to guard against bias introduced by accessing only self-selected participants in these panels.
Example: The information from the Nord-Trøndelag Health Study from Norway as one of the largest studies ever performed is especially suitable for epidemiologic studies on blood pressure, diabetes, quality of life, tuberculosis, and other lung diseases; along with data on cardiovascular diseases, lifestyle, disablement, work, and the working environment. https://www.ntnu.edu/hunt
Randomised clinical trials follow an
experimental design that involves primary data collection. An essential
guideline on clinical trials is the European Medicines Agency (EMA) Guideline for good clinical practice E6(R2), which specifies obligations for the conduct of clinical trials to
ensure that the data generated in the trial are valid. From a legal
perspective, the Volume 10 of the Rules Governing Medicinal Products in the
European Union contains all guidance
and legislation relevant for conduct of clinical trials. (see also Randomised controlled trials (RCT) ).
A number of documents are under revision. The way clinical trials are
conducted in the European Union (EU) will undergo a major change when the Clinical Trial Regulation (Regulation (EU) No 536/2014) will fully come into effect and will
replace the existing Directive 2001/20/EC. Envisaged 2021/2022.
Internationally, a few countries support the use of national health data for research purposes, which can provide extensive information like the prevalence of smoking and other health- related risk factors, obesity among other health ailments, access to health care, etc [1].
Examples: The National Minimum Data Set (NMDS) in New Zealand is a national collection of public and private hospital discharge information, including coded clinical information, for inpatients and day patients.
The National Cohort in Germany is a government-coordinated study collecting interview and self-completion questionnaires, several medical examinations and the collection of biological material (blood, urine, saliva, nasal swabs and stool from 100.000 women and 100.000 men, including a follow up assessment of all participants after 4 years. This will provide also molecular data on a broad scale (www.nako.de).
[1] Cox, S., 2016.
Annual Update of Key Results 2015/16: New Zealand Health Survey. Ministry of
Health, Wellington
and
Gliklich, R.E., Dreyer, N.A., Leavy, M.B., 2014. Registries for Evaluating Patient Outcomes: A User’s Guide [Online]. USA. Available from: https://www.ncbi.nlm.nih.gov/books/