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Under-reporting of serious adverse drug reaction in Sweden
Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience.
2004 (English)In: Pharmacoepidemiology and Drug Safety, ISSN 1053-8569, E-ISSN 1099-1557, Vol. 13, no 7, 483-487 p.Article in journal (Refereed) Published
Abstract [en]

INTRODUCTION: Adverse drug reactions (ADR) constitute a major problem, both from a medical point of view and as an economical burden. Spontaneous reporting of ADRs is one of the methods for post marketing surveillance of drug safety. Under-reporting can also provide an important obstacle to rapid and relevant signal detection. AIM: To investigate the rate of under-reporting serious ADRs of selected ICD 10 diagnoses. METHOD: In order to investigate the under-reporting rate we investigated at five hospitals within the county of Norrbotten in Sweden the total number of diagnosed cases during a period of 5 years (1996-2000) with the following diagnoses: cerebral haemorrhage (I 61.0-I 61.9), pulmonary embolism (I 26.0 and I 26.9), embolism or thrombosis (I 74.0-I 74.9), phlebititis, thrombophlebitits or venous thrombosis (I 80.0-I 80.3, I 80.8 and I 80.9) and portal vein thrombosis and other thrombosis or emboli (I 82.0-I 82.3, I 82.8 and I 82.9). The identity of these patients was obtained through a database search. The patients' case records were then scrutinized by a specially trained nurse and the drugs used at the time of the event were noted. An assessment of the possibility of an ADR was performed using standard WHO causality criteria. Later, database search in the Swedish ADR registry was performed in order to investigate whether these suspected ADRs had been reported to the national authority in Sweden or not. RESULTS: In total 1349 case records were found and scrutinized. Of these, 107 patients had received drugs that could have been a probable or possible cause to the diagnoses. Of these 92 cases had not been reported and only 15 patients were found in the database, giving an overall under-reporting rate of all ADRs of 86%. The most commonly occurring diagnoses were cerebral haemorrhage followed by venous thrombosis, 545 and 468 respectively. Among those cases that should have been reported according to the existing rules for spontaneous reporting of suspected ADRs the most frequently occurring diagnosis was cerebral haemorrhage (I 61.0) in connection to treatment with anticoagulants. CONCLUSION: The rate of spontaneous ADR reporting is very low, also for serious and fatal reactions.

Place, publisher, year, edition, pages
2004. Vol. 13, no 7, 483-487 p.
Keyword [en]
adverse drug reaction, spontaneous reporting, under-reporting
URN: urn:nbn:se:umu:diva-4556DOI: 10.1002/pds.962PubMedID: 15269932OAI: diva2:143704
Available from: 2005-04-29 Created: 2005-04-29 Last updated: 2012-01-31Bibliographically approved
In thesis
1. Spontaneous reporting of adverse drug reactions: Possibilities and limitations
Open this publication in new window or tab >>Spontaneous reporting of adverse drug reactions: Possibilities and limitations
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Adverse drug reactions (ADRs) constitute a major problem in society and in drug therapy. They are a common cause of short-term hospitalization, prolonged hospitalization and death. Spontaneous reporting of ADRs remains one the most effective methods for detecting new and serious drug reactions. In Sweden physicians are legally required to report fatal and serious ADRs. We know from previous studies that there is a substantial degree of under-reporting of ADRs also in Sweden.

Attitudes towards reporting of ADRs among physicians in the northern region of Sweden were investigated using a questionnaire. The most important factor for not reporting ADRs among physicians and general practioners in our region was that the reaction was considered to be well known. However, their attitudes could also allow for a considerable rate of under-reporting.

The effect on the reporting rate when nurses received instruction and were encouraged to report ADRs was studied. During a 12-month study period, 18 ADR reports with a total number of 22 ADRs were sent in by the nurses participating in the study to test nurses as reporters of ADRs.

Using the Swedish ADR database, we calculated the risk of agranulocytosis associated with the use of metamizole by using consumption data from the case records of scrutinized patients’ and stored prescriptions. Over the period from 1996 to 1999, ten cases of agranulocytosis during treatment with metamizole were reported to SADRAC. Metamizole was prescribed to 666 (19%) inpatients during the 3-month study period and 112 prescriptions were identified at the participating pharmacies. Thirty-eight percent of them indicated treatment for more than 15 days. Making certain assumptions, the calculated risk of agranulocytosis was one out of every 31 000 inpatients and one out of every 1400 outpatients. The degree of under-reporting of serious ADRs was studied in five hospitals. More than 1300 case records were scrutinized and among these we found 107 cases that according to current rules for ADR reporting, should have been reported. Only fifteen of these were found in the SADRAC database, indicating a under-reporting rate of 86%.The effect on the reporting rate of ADRs was studied in an intervention study in which a small economical inducement was given to those who reported ADRs.

The effect of a small economical stimulation to increase the reporting rate was studied. From the intervention area we received 62 suspected ADRs compared with 50 from the control area. The increase in the number of reports was 59% compared with an unchanged reporting rate from the control area.

The physicians in northern Sweden have a relatively good knowledge of the existing rules for ADR reporting. Nurses could play an important role in detecting and reporting suspected ADRs.

The risk of developing an metamizole induced agranulocytosis is considerably increased if metamizole is given to patients for a longer time than recommended. The rate of reported ADRs is very low, also for serious and fatal reactions. An increase in the reporting rate of suspected ADRs was observed during study period.

Place, publisher, year, edition, pages
Umeå: Farmakologi och klinisk neurovetenskap, 2005. 74 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 961
Pharmacology, adverse drug reactions, spontaneous reporting, metamizole, general practitioners, hospital physicians, under-reporting, economical inducement, nurses., Farmakologi
National Category
Pharmacology and Toxicology
Research subject
Clinical Pharmacology
urn:nbn:se:umu:diva-525 (URN)91-7305-868-8 (ISBN)
Public defence
2005-06-03, Föreläsningssal E04, 6A, Norrlands Universitetssjukhus, Umeå, 13:00 (English)
Available from: 2005-04-29 Created: 2005-04-29 Last updated: 2012-01-31Bibliographically approved

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Bäckström, MartinDahlqvist, Rune
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