Drug interactions are one of the problems caused by the irrational administration of drugs and one of the common causes of morbidity and mortality in patients. Since drug interactions are usually predictable, they are therefore avoidable and manageable. This study aimed to evaluate the frequency of drug interactions and their related factors in hospitalized patients of the intensive care unit in the Hamadan Besat hospital, Iran.

 

This cross-sectional study was performed on the clinical records of patients admitted to the intensive care unit (2019-2020) of Besat Hospital in Hamadan, Iran. This study was conducted on patients admitted to the intensive care unit of Besat Hospital after getting approval for the study, which was approved by the code of ethics (IR.UMSHA.REC.1398.026). Required information such as age, sex, length of stay in hospital and ICU, underlying disease, cause of hospitalization, height, weight, body mass index, smoking (yes, no), number of prescribed drug items, number of drug interactions, level of drug interactions risk level, the severity of interaction, level of documentation (from Up To Date site) and classification of interaction or the importance of drug interaction (from RxList site) and finally the patient's final condition (death, discharge, and recovery) were extracted from patients' clinical records. A checklist was registered. Completion of information was recorded in the Pre-Design checklist. Finally, the data was analyzed using SPSS software version 22 (SPSS Inc., Chicago, Ill., USA) and appropriate descriptive-analytical methods. 

The present study results, which was performed to determine the frequency of drug interactions and related factors in patients admitted to the intensive care unit of Besat Hospital of Hamadan University of Medical Sciences, showed that drug interactions were present in 94% of patients' records. The average number of total drug interactions per case was 5.94. The highest frequency of general interactions were found in anticonvulsants, anticoagulants, opioids, analgesics, cephalosporins, beta-blockers, nitroimidazoles, corticosteroids, antiplatelets, and antihypertensive inhibitors, respectively. Also, the most common cases of interaction were related to hospitalization causes of multiple trauma, intracranial hemorrhage, aortic artery thrombosis, and brain cancer.
In the present study, drug interactions were observed in 94% of the reviewed cases, which is a high and significant percentage. In previous studies, the percentage of drug interactions observed in the intensive care unit has been reported between 39% and 90.3%.
The results of the present study showed that the mean of interactions in each patient is 5.94. In other studies, different results were reported regarding the mean of the interactions that occurred in each patient. The results of some studies are similar to the present study. In the study of Rafiei et al. [22] in Kerman, the average number of drug interactions per patient was 6.1.
According to our findings, the intensity of interaction was moderate in most cases. Previous studies have reported varying degrees of drug interactions. In a study conducted in Pakistan, most cases of drug interactions were severe [20]. In other studies, severe drug interactions have been reported between 2.4 and 52% of the interactions [17, 26].
In the present study, there was a significant difference between the two sexes in terms of the average number of drug interactions per person, the level of documentation and the importance of drug interactions (P value <0.05);
The results of our study showed that drug interactions were significantly higher in patients whose final condition was reported as death than in patients whose condition was reported as recovery and discharge from the hospital. However, due to the complexity of the clinical condition of patients admitted to the intensive care unit, the high number of drug interactions cannot be considered as the main factor and determinant of the deterioration of the clinical condition and death of the patient. But at least it can be concluded that drug interactions may be effective along with other patients' clinical conditions.
Our study also showed that there is a positive and significant relationship between the length of hospital stay and the incidence of drug interactions, which were in line with previous studies [12, 19, 31].
Due to the fact that patients who usually stay longer in the hospital are in a more severe clinical condition, and as a result, the number of new drug items added to previous drugs is increased to improve the patient's treatment, there is a higher risk for drug interactions to occur.
Finally, the results of our study showed that in line with other studies, the incidence of drug interactions increases with age [20, 32]. Because older patients are at greater risk of drug interactions due to the presence of other concomitant diseases, especially liver and kidney diseases, as well as the use of a large number of drugs. In addition, the present study, in line with previous studies, showed that there is a positive and significant relationship between the number of drug items and the incidence of drug interactions [12, 19, 20, 33]. Therefore, it is necessary for patients who are being treated with more drugs to pay more attention to drug interactions. 

 

According to the results, prolonged stay in an intensive care unit, the elderly, and polypharmacy are the main essential factors associated with the occurrence of drug-drug interactions. These results indicate the importance of paying more attention to the monitoring and control of prescribed drugs in these patients. 

 

The researchers thank the Research Council of the Faculty and the Vice-Chancellor for Research and Technology of Hamadan University of Medical Sciences. The present article is the result of the doctoral dissertation of general medicine (design number: 9804112755), and the ethics committee of Hamadan University of Medical Sciences has approved it with the ethics ID IR.UMSHA.-REC.1398.026.

 

The authors declared no conflict of interest.