Methods In Pharmacoepidemiology

Methods In Pharmacoepidemiology By: Dr. Aqeel Nasim (M.Phil Pharmacy Practice) Pharmacoepidemiology is the study of drug-human populat...

Methods In Pharmacoepidemiology

By: Dr. Aqeel Nasim (M.Phil Pharmacy Practice)

Pharmacoepidemiology is the study of drug-human population interactions, looking at the benefits, risks, and usage of medications in real-life situations. Pharmacoepidemiology is concerned with medications and their pharmacological assessments, as well as the many methodologies used in epidemiology to analyse the benefits, dangers, and usage of drugs in real-life situations. Ad-hoc studies or database studies are pharmacoepidemiologic investigations (Sommet & Pariente, 2019).

There are specific ways for measuring drug exposure, as well as signs of drug compliance and misuse. In a world where a rising number of research rely on medico-administrative data, there are a variety of descriptive and explanatory study designs. In this setting, the usual constraints on study design are altered, with nearly any design chosen for the execution of a study from these databases emanating from a cohort in which data has been collected prospectively and thoroughly (Sommet & Pariente, 2019).

The descriptive (non-comparative) approach observes phenomena retrospectively, prospectively or transversally. ...

The analytic (comparative or etiologic) approach investigates putative associations between occurrence of (favorable or not) effects and exposure to one (or more) drug (s) (Montastruc et al., 2019).

Pharmacoepidemiology studies employ epidemiological reasoning, methods, and information to investigate the clinical use and effects of medications in human populations, including over-the-counter drugs, biologics, vaccinations, and medical devices, according to the World Health Organization.

Many of the CPCE's pharmacoepidemiology investigations are based on big health-care use databases and non-experimental examinations of pharmacological effects, both intentional and unexpected (Elseviers et al., 2016).

TYPES OF EPIDEMIOLOGICAL STUDIES

Observational Study

Participants in observational studies are observed without any forced changes in their conditions, i.e., without any intervention (Sedgwick, 2012). Observational studies aim to explore the ‘natural' condition of risk factors, diseases, or outcomes, despite the fact that participants' behaviour may change while they are being observed. When it comes to drug therapy, a group of people who are taking the medicine can be compared to a group of persons who are not taking the drug (Gilmartin-Thomas, Liew, & Hopper, 2018).

Summary of observational studies used in health research (Gilmartin-Thomas et al., 2018)

Study type	Purpose	Strengths	Limitations
Case reports and case series	Descriptive Usually first report of a notable issue	Easy to undertake Can provide detailed information to assist hypothesis generation	Not generalisible
Ecological studies	Descriptive Data at group/population level	Relatively easy to undertake Routinely collected data can be used	No data on individuals
Cross-sectional studies	Descriptive Profiling of a population or outcome of interest at a single time point	Relatively easy to undertake	Need for representative data
Case-control studies	Analytical Identify risk factors for a defined outcome (disease or condition)	Can be used to explore rare outcomes	Limited to a single outcome
Cohort studies	Descriptive and analytical Estimate the incidence of outcomes of interest as well as their determinants	Longitudinal Can be used to study multiple outcomes and multiple risk factors	Relatively difficult and expensive

Case reports and case series

Case reports, case series, and case study research are descriptive studies designed to illustrate unique, uncommon, or abnormal aspects discovered in patients in medical practise, and they may inspire new research topics. They are empirical studies of a patient or a group of patients in a realistic, real-world clinical context (Sayre, Toklu, Ye, Mazza, & Yale, 2017). Example: After developing intolerance to clozapine, a case report documenting the use of high-dose quetiapine in treatment-resistant schizophrenia was published.

Ecological studies

Individual-level data on the joint distribution of variables within groups are lacking in ecological studies because they focus on group comparisons rather than individual comparisons. Aggregate measurements, environmental measures, and global measures are all possible variables in an ecological study. Ecologic research designs may be divided into two categories: (a) whether the primary group is assessed (exploratory versus analytic study); and (b) whether participants are categorised by location (multiple-group study), time (time-trend study), or both place and time (place and time study) (mixed study) (Morgenstern, 1995).

Example: After the introduction of COX-2 inhibitors, there were variations in the rates of upper gastrointestinal bleeding (Mamdani et al., 2006).

Cross-sectional studies

Studies in which the presence or absence of disease or other health-related variables are determined in each member of the study population or in a representative sample at one particular time

Cross-sectional study is a form of observational research. The investigator does not change the exposure status because it is observational research. The researcher examines the relationship between the result and the exposure(s) in the population. A cross-sectional study's participants are chosen solely on the basis of the study's inclusion and exclusion criteria. After the research's participants have been chosen, the investigator monitors the study to analyse the exposure and outcomes (Setia, 2016c).

Example: Prevalence and knowledge of polycystic ovary syndrome (PCOS) among female science students of different public Universities of Quetta, Pakistan (Haq et al., 2017)

Figure: Example of Cross Sectional Study

Cohort studies

Cohort design is a form of observational or nonexperimental study design. In a cohort study, the participants do not have access to the desired outcome from the start. They are chosen based on the individual's exposure status. They are then tracked for a period of time to see if the desired effect occurs (Setia, 2016a).

Some research participants have been exposed (classified as exposed), whereas others have not (defined as unexposed). Some of the exposed individuals will develop the result of interest, whereas some of the unexposed individuals will develop the outcome of interest during the course of the study. The outcomes of these two groups will be compared.

Example: One prospective cohort study explored the relationship between the continuous use of antipsychotic drugs (exposure) and mortality (outcome) and hospitalisation (outcome) in older people (Chan et al., 2011)

Case-control studies

A case-control study is a form of observational research that examines variables linked to illnesses or outcomes (Setia, 2016b).

The case-control research begins with a set of cases, which are people who have the desired outcome. The researcher then attempts to create a second set of people, known as the controls, who are identical to the case people but do not have the desired outcome. The researcher next examines historical circumstances to see whether certain exposures are detected more frequently in the cases than in the controls. If an exposure is detected more frequently in cases than controls, the researcher might speculate that the exposure is connected to the desired outcome (Tenny, Kerndt, & Hoffman, 2017).

Example: The relationship between the use of antiplatelet and anticoagulant drugs (risk factor) and the risk of hospitalisation for bleeding (outcome) in older people with a history of stroke (Quilliam, Lapane, Eaton, & Mor, 2001)

Observational studies versus randomised controlled trials

Observational studies, in comparison to randomised controlled trials, are comparatively rapid, affordable, and simple to conduct. Observational studies have a considerably greater sample size than randomised controlled trials, allowing them to investigate an uncommon result. When a randomised controlled experiment would be unethical, they can be used instead. Observational studies, on the other hand, are unable to control for bias and confounding to the same level as clinical trials (Kovesdy & Kalantar-Zadeh, 2012).

References

Chan, T.-C., Luk, J. K.-H., Shea, Y.-F., Lau, K.-H., Chan, F. H.-W., Yu, G. K.-K., & Chu, L.-W. (2011). Continuous use of antipsychotics and its association with mortality and hospitalization in institutionalized Chinese older adults: an 18-month prospective cohort study. International psychogeriatrics, 23(10), 1640-1648.

Elseviers, M., Wettermark, B., Almarsdóttir, A. B., Andersen, M., Benko, R., Bennie, M., . . . Poluzzi, E. (2016). Drug utilization research: Methods and applications: John Wiley & Sons.

Gilmartin-Thomas, J. F., Liew, D., & Hopper, I. (2018). Observational studies and their utility for practice. Australian prescriber, 41(3), 82.

Haq, N., Khan, Z., Riaz, S., Nasim, A., Shahwani, R., & Tahir, M. (2017). Prevalence and knowledge of polycystic ovary syndrome (PCOS) among female science students of different public Universities of Quetta, Pakistan. Imperial Journal of Interdisciplinary Research, 35(6), 385-392.

Kovesdy, C. P., & Kalantar-Zadeh, K. (2012). Observational studies versus randomized controlled trials: avenues to causal inference in nephrology. Advances in chronic kidney disease, 19(1), 11-18.

Mamdani, M., Warren, L., Kopp, A., Paterson, J. M., Laupacis, A., Bassett, K., & Anderson, G. M. (2006). Changes in rates of upper gastrointestinal hemorrhage after the introduction of cyclooxygenase-2 inhibitors in British Columbia and Ontario. Cmaj, 175(12), 1535-1538.

Montastruc, J.-L., Benevent, J., Montastruc, F., Bagheri, H., Despas, F., Lapeyre-Mestre, M., & Sommet, A. (2019). What is pharmacoepidemiology? Definition, methods, interest and clinical applications. Therapies, 74(2), 169-174.

Morgenstern, H. (1995). Ecologic studies in epidemiology: concepts, principles, and methods. Annual review of public health, 16(1), 61-81.

Quilliam, B. J., Lapane, K. L., Eaton, C. B., & Mor, V. (2001). Effect of antiplatelet and anticoagulant agents on risk of hospitalization for bleeding among a population of elderly nursing home stroke survivors. Stroke, 32(10), 2299-2304.

Sayre, J. W., Toklu, H. Z., Ye, F., Mazza, J., & Yale, S. (2017). Case reports, case series–from clinical practice to evidence-based medicine in graduate medical education. Cureus, 9(8).

Sedgwick, P. (2012). Observational study designs. Bmj, 344.