1. Introduction
The elderly suffer from chronic diseases more than young adults, which is why multidrug therapy is more common in them. Some of these drugs are considered as inappropriate medications [1]. Numerous studies have been conducted around the world and in Iran on the Inappropriate Medication Use (IMU) in the elderly [2,3,4,5,6]. Recent studies have shown that there is a close relationship between the increased IMU and the incidence of physical and cognitive disorders [7, 8]. More studies on the IMU in the elderly can help prevent these complications and improve the health status of this population. Since no study has been conducted on the IMU among the elderly in northern Iran, this study aims to investigate the prevalence of IMU in the elderly living in northern Iran and prepare a list of inappropriate medications.

2. Methods & Materials
This study is a part of Amirkala Health and Ageing Project (AHAP) conducted as a cohort study on older adults since 2011. Age ≥60 years, residence in Amirkala county, and willingness to participate in the study were considered as inclusion criteria, while the lack of sufficient information was considered as the exclusion criterion [9]. The required information was collected by a two-part questionnaire with 17 items; the first part consists of 5 questions about the demographic characteristics of participants (age, marital status, level of education, employment status, smoking, underlying diseases, etc.) which was completed through interview, and the second part is a self-report with 12 items assessing the medication information (number and type of medication, and usage duration). Then, the IMU in the elderly was evaluated according to the 2012 Beers criteria [10] regarding the drugs that should not be prescribed in the elderly, the drugs that should be prescribed with caution, drug interaction, and the use of drugs with strong anticholinergic properties. The collected data were statistically analyzed in SPSS version 23 software by using chi-square test, Fisher’s exact test, and logistic regression analysis. The P≤0.05 was considered as the significance level.

3. Results
A total of 777 elderly people aged 60-92 years (Mean age= 69.71 years) participated in this study, of which 437 (56.2%) were male and 340 (43.8%) were female. A total of 292 older adults (37.58%) used inappropriate drugs according to Beers criteria. Among the inappropriate drugs, the most used drugs were glibenclamide (12.7%), diclofenac (8.8%) and clidinium-C (5.4%). Table 1 shows the results of chi-square test for evaluating the relationship between demographic variables and IMU.





As can be seen, the amount of used inappropriate drugs was significantly different between older men and women (P<0.001) where women used more inappropriate drugs than men. The IMU rate was higher in those aged> 80 years and there was a significant relationship between age and IMU (P<0.001). Educational level (P=0.036), employment status (P<0.001) and marital status (P=0.046) were another effective factors in IMU. Among the participants in this study, 13 (1.7%) used drugs that interacted with each other according to Beers criteria, where the most drug interaction was related to the concomitant use of anticholinergic drugs. Moreover, it was found that 75 older adults used drugs with anticholinergic properties. The highest frequency was related to Clidinium-C (4.6%).
Logistic regression analysis was used to determine the role of some variables affecting the IMU in the elderly. The results (Table 2) showed that gender, age >85 years, employment status and multidrug use (polypharmacy) had a significant effect on IMU where that the likelihood of using inappropriate drug in women was 1.427 times higher than in men (95%CI: 1.011-2.015).




Subjects over the age of 85 were 3.421 times more likely to use inappropriate drugs than those aged 60-64 years (95%CI: 1.011-2.015). The likelihood of taking an inappropriate drug in subjects with multidrug use was 4.19 times higher than those with no multidrug use (95%CI: 2.880-6.119).

4. Conclusion
The elderly in northern Iran are relatively exposed to IMU. Age over 85 years, employment status and multidrug use are the predictors of IMU. Older women use inappropriate medications more often than older men. Due to the fact that the side effects of taking inappropriate medications can be serious, proper administration of medications in the elderly is very important. Therefore, it is necessary to provide more educational courses to doctors, nurses and patients, and more supervision by the authorities.

Ethical Considerations
Compliance with ethical guidelines
This study was approved by the Ethics Committee of Babol University of Medical Sciences (MUBABOL.HRI.REC.1395.63). 

Funding
This article was extracted from PhD. dissertation of first author at Department of Pharmacology and Toxicology, School of Medical, Babol University of Medical Sciences, Babol.

Authors' contributions
Conceptualization: Seyed Reza Hosseini, Atena Rahimi; Methodology: Afsaneh Dadashi Haji, Ali Akbar Moghaddamnia, Ali Bijani; Investigation: Athena Rahimi, Seyed Reza Hosseini.

Conflicts of interest
All authors declare no conflict of interest.

Acknowledgements
The authors would link to thank Vice Chancellor for Research and Technology, Babol University of Medical Sciences.