Observational studies adverse reactions detected

Adverse event. Unwanted effects that occur and are detected in populations. The term is used whether there is or is not any attribution to a medicine or other cause. Adverse events may be known parts of a disease that are observed to occur within a period of observation, and they may be analyzed to test for their frequency in a given population or trial. This is done to determine if there is an unexpectedly increased frequency resulting from nondisease factors such as medicine treatment. The term adverse event or adverse experience is used to encompass adverse reactions plus any injury, toxicity, or hypersensitivity that may be medicine-related, as well as any medical events that are apparently unrelated to medicine that occur during the study (e.g., surgery, illness, and trauma). See definition of Adverse reaction. 

Phase IV. Studies or trials conducted after a medicine is marketed to provide additional details about the medicine s efficacy or safety profile. Different formulations, dosages, durations of treatment, medicine interactions, and other medicine comparisons may be evaluated. New age groups, races, and other types of patients can be studied. Detection and definition of previously unknown or inadequately quantified adverse reactions and related risk factors are an important aspect of many Phase IV studies. If a marketed medicine is to be evaluated for another (i.e., new) indication, then those clinical trials are considered Phase II clinical trials. The term postmarketing surveillance is frequently used to describe those clinical studies in Phase IV (i.e., the period following marketing) that are primarily observational or nonexperimental in nature, to distinguish them from well-controlled Phase IV clinical trials or marketing studies. 

Over 30 billion tablets of NSAID were dispensed in the United States in 2000 approximately 16% represent prescriptions for NSAIDs [43]. These compounds enjoy a remarkable benefit/risk ratio when used in the treatment of acute self-limited pain syndromes. However, when taken chronically by the elderly or individuals with certain co-morbid conditions, the frequency of adverse reactions rises dramatically. Unfortunately, the real incidence of nephrotoxicity due to NSAIDs is unknown due to a lack of an accurate method of detection. The overall incidence could be very low, considering that up to 40 million people in the United States take NSAIDs on a regular basis [44]. In the 10 year-period 1972-1982,8 miUion prescriptions for mefenamic acid were given in the United Kingdom, and only 23 cases of mefenamic acid nephropathy were observed [45]. This is in contrast to the higher incidence of nephrotoxicity in selected and prospective studies. Corwin and Bonventre [46] found that renal insufficiency secondary to NSAIDs accounted for approximately 6% of cases of ARF seen during a two-year period. In a prospective collaborative study, NSAIDs rep-... 

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