Impact on practice

  • Medication errors at the community pharmacy are mainly related to prescribing and dispensing errors.

  • Most of the prescription corrections by pharamcists in Spain are related to strength, quantity or dosage; less frequent are errors where no route is specified and lack of prescriber information.

  • Community pharmacists can effectively participate in medication error management to improve patient safety.

Introduction

The National Coordinating Council for Medication Error Reporting and Prevention (NCCMERP) from the United States defines medication error as “any preventable event that may cause or lead to inappropriate medication use or patient harm, while the medication is in the control of the health-care professional, patient or consumer [1].”

Medication safety has long been a key issue within the broader patient safety spectrum. A number of studies have shown that medication errors are relatively common, and they have identified a range of contributing factors that occur on individual and organizational levels. Much of this research has been conducted in secondary care settings, with relatively few studies taking place in primary care, and fewer still focusing on how community pharmacies dispense medicine. However, a large portion of medication prescribing and dispensing occurs in primary care settings [2]. Compared with the hospital sector, there is little data concerning the epidemiology and typology of errors in primary care, particularly in relation to community pharmacies [3]. In Spain, the Pharmacy Office (Community Pharmacy) is a private health establishment run for the public interest, wherein autonomous communities are subject to health planning, with which the owner-pharmacist works through aides or assistants [4]. The pharmacies dispense drugs to patients covered by the National Health System under the conditions set forth in the regulations [5].

The professional functions of pharmacists have changed from a passive to a more active role; now pharmacists personally follow up with patients [6]. The pharmacy technician assists the pharmacist in the dispensing of pharmaceutical products; controls inventory and the organization of pharmaceutical products; and evaluates the user’s physiological parameters and vital signs under the pharmacist’s supervision [7].

This study investigates the nature, frequency and potential causes of medication errors in a community pharmacy in Madrid, Spain.

Method

Setting

The study was conducted over a 13-month period (February 2010–March 2011) at a community pharmacy in Madrid. Pharmacists and pharmacy technicians who worked there were invited to participate; 2 pharmacists and 2 pharmacy technicians agreed to partake.

Inclusion/exclusion criteria

All prescriptions for medicines that were offered during the period of study to the community pharmacy by any patients had to be included. Medication errors were all prescriptions that required intervention by the pharmacy on that particular day (even if actual dispensing took place on another day). Reasons for including a prescription intervention as a medication error were defined according to the different situations considered as causes of medication errors in the study.

Prescriptions outside the social security system were excluded due to the difficulty in establishing contact with the centres and physicians who provided the prescriptions and to the short time available in the pharmacy to carry out research activities. Prescription of other health care products (e.g. dressings, incontinence materials, syringes and needles) were excluded.

Data collection

A team of two pharmacists categorized the reported incidents according to medication error as prescribing errors, dispensing near-misses and dispensing errors. Table 1 sets forth this study’s concepts. In cases of dispensing near-misses, the classification was made anonymously by each team member who nearly committed the error, marking each incident according to an internal code. During the review process, these incidents were marked and their classifications rechecked for each category; with all patients and healthcare providers remaining anonymous. We obtained ethical approval from the local research ethics committee.

Table 1 Definitions used in the study
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Method validation

A team of two pharmacists categorized the reported incidents according to the categories established. While pharmacists and technicians tend to be on opposite shifts, it was possible to make a cross-evaluation of the reported incidents and their classifications. In cases of doubt, a third skilled pharmacist outside the study was consulted. There was consensus among the researchers about which prescriptions constituted an incident. Moreover, there were no variations in the interpretation of this study’s concepts.

Backgrounds/causes of medication errors

The data included three types of written reports of incidents: prescribing errors, dispensing near-misses, and dispensing errors. All prescriptions were assessed according to the situations that led to their inclusion in the study. These criteria were established after taking into account some published studies relating to the proximal causes of medication error [8, 9]. Table 2 shows all causal situations and their grouping into three major categories of medication errors used in the study.

Table 2 Causes of medication errors (n = 2117)
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Data analysis

From a prescribing standpoint, practices related to the transcription and transmission of prescription information may contribute to patients not receiving the intended medication or dose. Only errors made in the process of medication ordering, transcription and dispensing were documented; errors in drug administration were not considered.

The error rate was calculated with 95 % confidence intervals. The medication error rate was determined by calculating the percentage of errors [12]. Descriptive Statistics were computed by the Statistical Package for the Social Sciences (Release 11.0) software.

Results

The sample consisted of 42,000 prescriptions, yielding 2,117 medication errors; there were 1,127 prescribing errors, 216 dispensing errors, and 774 near-misses. On the basis of the number of prescriptions handled during the study period, we calculated an error rate of 5.0 % (95 % confidence interval 4.8–5.2 %) (Table 2).

Prescribing errors were the most frequent type of error, related to prescription illegibility (26.2 %), medication, strength, quantity or dosage non-existence (6.3 %), lack of prescriber information (4.8 %), no route specified (2.9 %), problems with subsidies (3.4 %), medicine no longer in stock (1.4 %), the patient wanted to change the prescription (3.8 %), and medicine not immediately in stock (4.1 %).

Out of 2,117 medication errors detected, 36.5 % corresponded to near-misses and 10.2 % to dispensing errors. The most common types of dispensing errors or near-misses appeared to be prescriptions with incompletely specified dosages or frequency (17.8 %), followed by missing or wrong patient identification (12.6 %).

Other causes included substitution of medicine (4.4 %), drug indicated but dosage inappropriate (1.5 %), wrong drug dispensed (4.4 %), drug duplication (3.6 %) (e.g., prescribing Panadol and Tylenol at the same time, both compounds containing acetaminophen), and drug–drug interaction (2.0 %) (e.g., prescribing aspirin along with a blood thinner). The error rate for near-misses and dispensing errors were 1.8 and 0.5 %, respectively.

When errors were grouped by cause, the most common cause of error was prescription-based (73.6 % of errors). The most common causes for this category were prescribing errors requiring correction (97.4 %), where an illegible prescription (49.2 %) represented the major cause of error. Other causes related to non-specificity and missing information from patients and prescribers. Problems related to subsidies were present for 6.3 %.

The second most common cause of error was transcription-based (18.4 %), and these errors were quite diverse. Again, illegible prescriptions and incomplete prescription dosage and frequency information were the most frequent, followed by wrong drug provision. Fewer of the pooled dispensing errors occurred (7.8 %), the majority being “wrong strength” (e.g., 25 mg instead of 50 mg) and “wrong dosage.” The most frequently occurring errors in the transcription stage were in the categories “wrong strength”, “wrong medicine”, and “wrong dosage.”

Discussion

Our results show that prescribing errors requiring correction were the most frequent type of error, illegible prescriptions being the most common (26.2 %). The medication error rate found by this study was 5 %. Similar results were obtained in the study developed by Knudsen et al. [13] at a community pharmacy.

Most of the prescription errors were related to strength, quantity or dosage; others to no route specified and lack of prescriber information. The prescription correction rate estimated was 53.2 %. A similar study developed at a Mexican primary care university clinic revealed 58 % of inappropriate prescriptions, mostly due to errors on dosage regimen and inappropriate drug selection [14]. According to the number of prescriptions handled, our prescribing error rate is lower than that reported in other studies with a similar quantity [15].

As seen in other studies, the rate of near-misses was greater than the rate of dispensing errors [16, 17]. This finding indicates that quality control in community pharmacies plays a crucial role in preventing errors from affecting patients [18].

Most of the errors that occurred were reported in the prescribing stage. This finding is consistent with those of other studies [19] in which the prescribing stage has been reported to be the most susceptible to errors, accounting for 49 % of serious medication mistakes [20]. Incorrect or missing dosage levels, the wrong drug or wrong therapeutic choice, and drug interactions were consistently identified in other studies as the most common types of prescribing errors at ambulatory care facilities [21].

We found more errors that could be associated with medication knowledge deficiency and significantly fewer prescribing errors associated with patient knowledge deficiency. Our analysis assumed that the physician knew the details of the patient’s condition but failed to recognize the indications, contraindications, or dosing guidelines of the drug. Other studies have shown that inadequate drug knowledge by many healthcare professionals is a risk factor in prescription errors [22, 23].

The prescribing error rate reported may also be due to the lack of electronic prescriptions and computer prescription systems. Currently, we cannot address the global adoption of electronic prescribing; a number of European countries such as Britain and Spain are still struggling to implement an integrated digitized module [24]. The positive effects of Electronic Prescribing on Medication Errors and Adverse Drug Events have been widely documented [25–27].

The results show that errors at the transcription stage occur twice as often as those in the dispensing stage. According to other studies, transcription errors are common [28, 29]. Our results differ statistically from those reported by other researchers. Two reasons for these differences include the location of the studies (community/private pharmacies versus pharmacies embedded within primary health care settings) and the absence of mechanisms that facilitate effective communication with physicians regarding prescription-related concerns [30].

Compared with previous studies, our dispensing error rate was significantly lower [31]. We found that the most common error types were the wrong drug, drug duplication and wrong dosages. These findings are consistent with previous studies indicating that improper dosage and incorrect dosage form are among the most frequent error types [32].

Possible explanations of dispensing errors include the lack of a safe systematic procedure for dispensing medicines in the pharmacy and the need to separate drugs with a similar name or appearance. From a socio-technical point of view, other causes could be related to the volume of prescriptions handled; according to Seoane-Vazquez [33], there is a correlation between these two.

Study limitations

The findings in the present study are based on medication errors found in only one community pharmacy in its routine quality control documentation. The strength of this study is that the incidents documented herein reflect the community pharmacy staff’s recognition of its errors. An English study showed that under-reporting of incidents in a community pharmacy is probably a considerable problem, and in most cases the staff would not report incidents, especially if the patient were not likely to complain outside the pharmacy [16].

As the data are based on self-reported errors found during routine recording, under-reporting cannot be ruled out. Therefore, the data represents a conservative estimate of the frequency of errors. It would be interesting to know whether identification of errors by direct observation instead of spontaneous self-reporting would result in a higher rate of errors, as seen in hospital studies [34].

The study’s reliability would have been strengthened if we could have had a skilled clinical pharmacologist as a supervisor; it would also have been preferable to have more precise instructions relating to the medication error categories, but this was not possible in the present study.

Conclusion

This study explored the nature, frequency and potential causes of medication errors at a community pharmacy in Madrid, Spain. The results showed that prescribing errors were the most frequent type of error reported and that the error rate was 5 %; most of the errors that occurred were reported in the prescribing stage.

This study has shown the continued incidence of medication errors in the health care system and the possibility of detecting them at a community pharmacy. Analysis of these errors can contribute to greater patient safety by serving as the basis of a future project to study the impact and gravity of pharmaceutical interventions vis-à-vis medication errors.