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The Pattern of Abbreviation Use in Prescriptions: A Way Forward in Eliminating Error-Prone Abbreviations and Standardisation of Prescriptions N.R. Samaranayake*,1,2, P.R.L. Dabare2, C.A. Wanigatunge3 and B.M.Y. Cheung1

1Department of Medicine, Faculty of Medicine, The University of Hong Kong, Hong Kong 2Department of Medical Education and Health Sciences, Faculty of Medical Sciences, University of Sri Jayewardenepura, Sri Lanka 3Department of Pharmacology, Faculty of Medical Sciences, University of Sri Jayewardenepura, Sri Lanka

Abstract: Introduction and Objectives: Inappropriate abbreviations used in prescriptions have led to medication errors. We investigated the use of error-prone and other unapproved abbreviations in prescriptions, and assessed the attitudes of pharmacists on this issue.

Methods: A reference list of error-prone abbreviations was developed. Prescriptions of outpatients and specialty clinic patients in a teaching hospital in Sri Lanka were reviewed during one month. An interviewer administered questionnaire was used to assess attitudes of pharmacists.

Results: 3370 drug items (989 prescriptions) were reviewed. The mean (standard deviation) number of abbreviations per prescription was 5.9 (3.5). The error-prone abbreviations used in the hospital were, µg (microgram), mcg (microgram), u (units), cc (cubic centimeter), OD (once a day), @ sign, d (days/daily), m (morning) and n (night), and among all prescriptions reviewed, they were used at a rate of 17.4%, 0.1%, 1.9%, 0.2%, 0.2%, 4.9%, 23.5%, 4.4% and 15.8% respectively. Among the 103 types of abbreviations observed, 71 were not standard acceptable abbreviations. Multiple abbreviations were used to indicate a single drug item/ instruction (N = 7). The abbreviation ‘d’ was used to denote ‘daily’ as well as ‘days’. All pharmacists believed that using error-prone abbreviations will always (5.3%) or sometimes (94.7%) lead to medication errors.

Conclusions: Error-prone abbreviations and many other unapproved abbreviations are frequently used in hospitals. There is a need to educating health care professionals on this issue and introduce an in-house error-prone abbreviation list for their guidance.

Keywords: 'Do Not Use' list, error-prone abbreviations, Medication errors, prescriptions; Sri Lanka, unapproved abbreviations

INTRODUCTION

The use of inappropriate abbreviations in prescriptions may alter intended therapeutic outcomes and even cause unnecessary harm to patients [1, 2]. Many safety organisations have cautioned this malpractice and have even highlighted some abbreviations that are frequently associated with medication errors [3-5]. Despite these warnings, error-prone abbreviations continue to be used [6]. The rapid evolvement of electronic prescriptions have minimised this problem to an extent [7], but hand-written prescriptions will continue to be used, especially in developing countries [8, 9]. Therefore eliminating error-prone abbreviations and standardising acceptable abbreviations is an urgent need. In order to achieve this goal, it is first important to identify the types and frequencies of inappropriate abbreviations used in prescriptions. Secondly, it is important to assess the attitudes of prescription interpreters, mainly

*Address correspondence to this author at the Department of Medical Education and Health Sciences, Faculty of Medical Sciences, University of Sri Jayewardenepura, Sri Lanka; Tel: 00194714467919; E-mail: nithushisamaranayake@yahoo.com

pharmacists, to determine the difficulties associated with reading and interpreting abbreviations. Unfortunately, abbreviations are not used consistently and may differ by country, setting or hospital [10-13]. Therefore, even if similar studies exist, these findings may not be completely applicable to all settings. Many safety organisations have introduced ‘Do Not Use’ lists; lists that specify error-prone abbreviations that should be avoided by doctors when prescribing [3-5]. Although our previous work has suggested that this intervention is effective [14], the success would largely depend on introducing a comprehensive error-prone abbreviation list that would target inappropriate practices of a particular setting. As the pattern of using abbreviations vary among different settings, directly adopting error-prone abbreviation lists from other countries may not always be appropriate. Therefore we first compared error-prone abbreviations lists introduced by several internationals safety organisations [3-5, 15] in order to compile a comprehensive reference list. Using this reference, we aimed to identify error-prone abbreviations used in prescriptions of the study hospital. We also aimed to identify other potentially dangerous unapproved abbreviations (not listed as error-prone

2 Current Drug Safety, 2014, Vol. 9, No. 1 Samaranayake et al.

abbreviations), identify multiple abbreviations used to denote the same drug or instruction, and to identify instances where a single abbreviation has multiple intended meanings. We then aimed to ascertain attitudes of pharmacists regarding the use of inappropriate abbreviations in prescriptions. Using this information, we aimed to determine the suitability of developing an in-house error-prone abbreviation list against directly adopting lists recommended in other countries.

METHODS

The study was conducted in a university affiliated tertiary care hospital (herein after referred to as the study hospital) with 34 wards, 7 specialty units, 12 operating theaters and a bed strength of 1073 beds. Apart from the in-patient care, the hospital’s out-patient services include the operation of 35 specialty clinics, accident & emergency, trauma and out-patient care department (OPD). The pharmacy department is mainly divided as indoor and outdoor pharmacies. The outdoor pharmacy dispenses drugs to the clinic patients and OPD patients, while the indoor pharmacy distributes drugs to the wards. As the hospital adopts a ward-stock method of drug distribution, pharmacists in the indoor pharmacy do not come into direct contact with prescriptions. Therefore only prescriptions and pharmacists related to the outdoor pharmacy were included in this study. We included prescriptions dispensed to OPD patients and 13 specialty clinics (medical, surgery, cardiology, neurology, endocrinology, skin, diabetes, peadiatrics, psychiatry, gastroenterology, cancer, asthma and hypertension clinic).

THE STUDY PROCESS

Development of an Error-Prone Abbreviations Reference List

Error-prone abbreviations introduced by the Institute of Safe Medication Practices [3], the Joint Commission on Accreditation of Healthcare Organizations of the USA [4], Hospital Authority of Hong Kong SAR [15] and Australian Commission on Safety and Quality in Healthcare [5] were compared and a reference list of error-prone abbreviations was prepared by the study pharmacists. The comparison of error-prone and standard abbreviations introduced by different safety organisations are shown in Table 1. According to the comparison, the Institute of Safe Medication Practices [3] and the Australian Commission on Safety and Quality in Healthcare [5] introduced a wide list of error-prone abbreviations compared to the lists introduced by the Joint Commission [4] and the Hospital Authority of Hong Kong. Of note, abbreviations ‘IU’ (international units), ‘QD’ (once daily), ‘QOD’ (every other day), ‘u’ (units), trailing zero and lack of leading zero were highlighted by all four lists. ‘µg’ (microgram) and ‘OD’ (once daily) were highlighted in three lists. The reference list of error-prone abbreviations developed for this study incorporated abbreviations specified in all four lists (Table 2a). Two clinical pharmacologists reviewed and endorsed the reference list.

The Prescription Review Process

Abbreviations used in prescriptions were reviewed by two study pharmacists and were recorded in a pre-determined data collection form. Abbreviations used for indicating drug names, instructions, route of administration and frequencies were documented. The prescriptions were randomly selected at any stage during the dispensing cycle. Prescriptions applicable to the latest clinic date were reviewed in patients who maintained a clinic book, and all reviewed prescriptions were tagged to avoid selecting the same prescription again. The audit was conducted for a period of one month on weekdays. Conducting the study for one month ensured that a representative sample of all clinic prescriptions was included, as generally all clinic patients revisit the clinic once a month. A sample of 50 prescriptions was reviewed and recorded by both study pharmacists, the records were compared and % of agreement was calculated using the kappa value. Discrepancies were discussed and a uniform method of interpreting prescriptions and recording were agreed upon. This ensured that variances in the ability to read and interpret handwritten prescriptions did not differ among the two study pharmacists. Error-prone abbreviations were determined according to the developed reference list. Abbreviations that were not categorised as error-prone, but did not comply with, the standard abbreviation list of the Hospital Authority of Hong Kong (Table 2b), and the list of acceptable terms or abbreviations of the Australian Commission on Safety and Quality in Healthcare [5] were grouped as ‘other unapproved abbreviations’. Abbreviations that had more than one intended meaning and full names that were represented by more than one abbreviation were also noted.

Sample Size Determination

Approximately, 103,235 patients visit the outdoor pharmacy every month and using a 5% margin of error, 95% confidence interval and a 50% response distribution, 383 prescriptions were calculated as a representative sample for review (Raosoft. Inc, 2004, Seattle, WA). The proportions of prescriptions to be included from the OPD and the different specialty clinics were determined based on the out-patient and clinic attendance, and through expert opinion.

The Survey Process

To complement the prescription review process and obtain qualitative data, a survey was conducted. An interviewer administered questionnaire was developed and all 19 pharmacists who were attached to the outdoor pharmacy were invited for the survey. Demographic information and attitudes on abbreviations were assessed in the questionnaire. The English version of the questionnaire was validated by five academic pharmacists (not included as study participants) before conducting the survey. Each question was validated on its relevance to the objective, appropriateness of response options, clarity to the reader, whether testing what was intended by researcher, and if re-wording was needed, using a five point ordinal scale. According to their comments, two questions were modified

The Pattern of Abbreviation Use in Prescriptions Current Drug Safety, 2014, Vol. 9, No. 1 3

Table 1. Comparison of Error-Prone Abbreviations Listed by Different Safety Organisations

Error-Prone Abbreviation Intended Meaning ISMP JCAHO HAHK ACSQH

µg Microgram ü ü ü

mcg Microgram ü ü

BID or bid Twice a day ü

AD, AS, AU Right ear, left ear, each ear ü

OD, OS, OU Right eye, left eye, each eye ü

OW Once week ü

p/f Per fortnight ü

BT Bedtime ü ü

cc Cubic centimeters ü ü

D/C Discharge or discontinue ü ü

e/ E Eye ü

gtt or gutte Drops ü

IJ Injection ü ü

IN Intranasal ü ü

IT Intrathecal ü

HS or hs Half-strength at bedtime, hours of sleep ü ü

IU** International units ü ü ü ü

o.d. or OD Once daily ü ü ü

OJ Orange juice ü ü

Per os By mouth, orally ü

Pulv Powder ü

q.d. or QD** Every day ü ü ü ü

q.h Every hour ü

qhs Nightly at bedtime ü ü

qn Nightly or at bedtime ü

q.o.d. or QOD Every other day ü ü ü ü

q1d Daily ü

q6PM, etc. Every evening at 6 PM ü ü

SC, SQ, sub q Subcutaneous ü ü

SL Sublingual ü

ss Sliding scale (insulin) or ½ (apothecary) ü ü

SSRI Sliding scale regular insulin ü ü

SSI Sliding scale insulin ü ü

i/d, i/D One daily ü ü

TIW or tiw Three times a week ü ü

TID Three times a day ü

U or u** Unit ü ü ü ü

UD As directed (“ut dictum”) ü

Ung Ointment ü

M or m Morning ü

N or n Night ü

4 Current Drug Safety, 2014, Vol. 9, No. 1 Samaranayake et al.

(Table 1) contd…..

Error-Prone Abbreviation Intended Meaning ISMP JCAHO HAHK ACSQH

Occ or oc Eye ointment ü

Mist Mixture ü

Trailing zero - ü ü ü ü

Lack of leading zero - ü ü ü ü

Large doses without properly placed commas 100,000 units 1,000,000 units ü ü

APAP acetaminophen ü

ARA A vidarabine ü

AZT zidovudine (Retrovir) ü

CPZ compazine (prochlorperazine) ü

DPT Demerol-Phenergan-Thorazine ü

DTO Diluted tincture of opium, or deodorized tincture of opium ü

HCl hydrochloric acid or hydrochloride ü

HCT hydrocortisone ü

HCTZ hydrochlorothiazide ü

MgSO4 magnesium sulfate ü

MTX methotrexate ü

PCA procainamide ü

PTU propylthiouracil ü

T3 Tylenol with codeine No. 3 ü

TAC triamcinolone ü

TNK TNKase ü

ZnSO4 zinc sulfate ü

“Nitro” drip nitroglycerin infusion ü

“Norflox” norfloxacin ü

“IV Vanc” intravenous vancomycin ü

x3d For three days ü ü

> and < Greater than and less than ü ü

/ (slash mark) Separates two doses or indicates “per” ü ü

@ At ü ü

& And ü ü

+ Plus or and ü ü

° Hour ü ü

. o r . zero, null sign ü

MS Morphine sulphate or magnesium sulphate ü ü

MSO4 Morphine sulphate ü ü

6/24 Every six hours ü

1/7 For one a day ü

½ Half ü

106 One million ü ü, present ; ISMP, Institute of Safe Medication Practices; JCAHO, Joint Commission on Accreditation of Healthcare Organization; HAHK, Hospital Authority of Hong Kong; ACSQH, Australian Commission on Safety and Quality in Healthcare.

The Pattern of Abbreviation Use in Prescriptions Current Drug Safety, 2014, Vol. 9, No. 1 5

Table 2a. Reference List of Error-Prone Abbreviations

Error-Prone Abbreviation Intended Meaning

µg Microgram

Mcg Microgram

BID or bid Twice a day

AD, AS, AU Right ear, left ear, each ear

OD, OS, OU Right eye, left eye, each eye

OW Once week

p/f Per fortnight

BT Bedtime

cc Cubic centimeters

D/C Discharge or discontinue

e/ E Eye

gtt or gutte Drops

IJ Injection

IN Intranasal

IT Intrathecal

HS or hs Half-strength at bedtime, hours of sleep

IU International units

o.d. or OD Once daily

OJ Orange juice

Per os By mouth, orally

Pulv Powder

q.d. or QD Every day

q.h Every hour

qhs Nightly at bedtime

qn Nightly or at bedtime

q.o.d. or QOD Every other day

q1d Daily

q6PM, etc. Every evening at 6 PM

SC, SQ, sub q Subcutaneous

SL Sublingual

ss Sliding scale (insulin) or ½ (apothecary)

SSRI Sliding scale regular

SSI Sliding scale insulin

i/d, i/D One daily

TIW or tiw Three times a week

TID Three times a day

U or u Unit

UD As directed (“ut dictum”)

Ung Ointment

M or m Morning

(Table 2a) contd…...

Error-Prone Abbreviation Intended Meaning

N or n Night

Occ or oc Eye ointment

Mist Mixture

Trailing zero -

Lack of leading zero -

Large doses without properly placed commas 100,000 units 1,000,000 units

APAP acetaminophen

ARA A vidarabine

AZT zidovudine (Retrovir)

CPZ compazine (prochlorperazine)

DPT Demerol-Phenergan-Thorazine

DTO Diluted tincture of opium, or deodorized tincture of opium

HCl hydrochloric acid or hydrochloride

HCT hydrocortisone

HCTZ hydrochlorothiazide

MgSO4 magnesium sulfate

MTX methotrexate

PCA procainamide

PTU propylthiouracil

T3 Tylenol with codeine No. 3

TAC triamcinolone

TNK TNKase

ZnSO4 zinc sulfate

“Nitro” drip nitroglycerin infusion

“Norflox” norfloxacin

“IV Vanc” intravenous vancomycin

x3d For three days

> and < Greater than and less than

/ (slash mark) Separates two doses or indicates “per”

@ At

& And

+ Plus or and

° Hour

. o r . zero, null sign

MS Morphine sulphate or magnesium sulphate

MSO4 Morphine sulphate

6/24 Every six hours

1/7 For one a day

½ Half

106 One million

6 Current Drug Safety, 2014, Vol. 9, No. 1 Samaranayake et al.

Table 2b. Standard Abbreviation List of the Hospital Authority of Hong Kong

Approved Abbreviations for Drug Names

Full Name Abbreviation

Acetomenaphthone Vit K4

Adenosine Triphosphate ATP

Adrenocorticotrophic Hormone ACTH

Adsorbed Diphtheria & Tetanus Vaccine DT

Adsorbed Diphtheria, Tetanus & Pertussis Vaccine DTP

Alpha Tocopheryl Acetate Vit. E

Alpha Tocopheryl Nicotinate Vit. E

Ascorbic Acid Vit. C

Bacillus Calmette Guerin Vaccine BCG Vaccine

Calcium Carbonate CaCO3

Calcium Chloride CaCl2

Carmustine BCNU

Cisplatin CDDP

Cyanocobalamin Vit. B12

Cytarabine Ara-C

Desmopressin DDAVP

Ergocalciferol, Calciferol Vit. D2

Erythropoietin EPO

Etoposide VP-16

Ferrous Sulphate FeSO4

Filgrastim G-CSF

Fluorouracil 5-FU

Glyceryl Trinitrate GTN, TNG

Hepatitis B Immune Globulin HBIG

Isoniazid INAH

Lomustine CCNU

Magnesium chloride MgCl2

Magnesium Sulphate MgSO4

Measles/Mumps/Rubella Vaccine MMR Vaccine

Mercaptopurine 6-MP

Methotrexate MTX

Molgramostim GM-CSF

Phenoxymethylpencillin Pencillin V

Phytomenadione Vit. Kl

Potassium Chloride KCl

Potassium Iodide KI

Potassium Permanganate KMnO4

Propylthiouracil PTU

Prostaglandin E2 PGE2

Pyridoxine Hydrochloride Vit. B6

(Table 2b) contd…..

Approved Abbreviations for Drug Names

Full Name Abbreviation

Riboflavine Vit. B2

Sodium Bicarbonate NaHCO3

Sodium chloride NaCl

Teniposide VM-26

Thiamine Vit. B1

Thyrotrophin-releasing hormone TRH

Thyroxine T4

Liothyronine Sodium T3

Zinc Oxide ZnO

Balance Salt Solution BSS

Dihydrocodeine Tartrate DF118

Expectorant Stimulant MES

Hydrocortisone 1% & Clioquinol 3% H1V3

Multivitamin MV

Vitamin B Complex Vit.B Co

Approved Abbreviations for Route of Administration

Full Name Abbreviation

Intradermal I.D.

Intramuscular I.M.

Intravenous I.V.

Intraperitoneal I.P.

Nasogastric N.G.

Per oral P.O.

Per rectum P.R.

Per vagina P.V.

Subcutaneous S.C.

Sublingual S.L.

and one question was added. The questionnaire was translated to Sinhalese language and the validity of the translation was assessed by a back translation method. Ethical approval was obtained from the Ethics Review Committees of the Faculty of Medical Sciences, University of Sri Jayewardenepura, Sri Lanka and the Colombo South Teaching Hospital, Sri Lanka. Informed consent was obtained from all participants before the survey.

Statistical Analysis

Data were analysed using SPSS 19.0 (IBM Corporation, Armonk, NY). The number of drug items prescribed in each phase was used as the denominator for calculating percentages in the prescription review study and the number of pharmacists that responded to the survey was used as the denominator when analysing survey results.

The Pattern of Abbreviation Use in Prescriptions Current Drug Safety, 2014, Vol. 9, No. 1 7

RESULTS

989 prescriptions that included 3370 drug items were reviewed in the study hospital. The mean (standard deviation) number of abbreviations per prescription was 5.9 (3.5). According to the reference list, the types of error-prone abbreviations used by prescribers and the rate of usage are shown in Table 3. ‘µg’ (microgram), ‘d’ (days/daily) and ‘n’ (night) were the most commonly used error-prone abbreviations in the study hospital. Among the 103 types of abbreviations observed, 71 were unapproved (Table 3). Multiple abbreviations were used to indicate a single drug item/ instruction in 7 instances (Table 4). The abbreviation ‘d’ was used to denote ‘daily’ as well as ‘days’. Table 3. Error-Prone and Some Other Unapproved

Abbreviations Used in the Study Hospital

Abbreviation Percentage of Usage*

Error-Prone Abbreviations

d (days/daily) 23.5

µg (microgram) 17.4

n (night) 15.8

m (morning) 4.4

@ sign 4.9

u (units) 1.9

cc (cubic centimeter) 0.2

OD (once a day) 0.2

mcg (microgram) 0.1

Some Frequently Used Unapproved Abbreviations

pcm/PCM (paracetamol) 5.2

LA (local application) 2.2

MS (methyl salicylate) 1.9

o (oral) 1.5

syr/sy (syrup) 1.3

BCo (vitamin B complex) 0.8

DFS (diclofenac sodium) 0.7

HCT (hydorchlorothizide) 0.7

ISMN (isosorbide mononitrate) 0.7

tsp/ TSP (teaspoon) 0.6

EOD (every other day) 0.5

FA (folic acid) 0.5

α or 1α (1α colecalciferol) 0.3

ASP (Aspirin) 0.3

MSLA (methyl salicylate local application) 0.3

ISDN (isosorbide mononitrate) 0.2 *The number of drug items reviewed (N= 3370) was used as the denominator. Only 1/9 error-prone abbreviations used in the study hospital was cautioned by all four error-prone abbreviation

lists. 2/9 error-prone abbreviations were cautioned by 3 of the lists and 4/9 were cautioned by 2 lists. All the pharmacists (N=19) who were invited, responded to the survey. Their demographic characteristics are shown in Table 5. Most pharmacists were 31–40 years of age and most were females. The minimum qualification required to be recruited as a pharmacist in a Sri Lankan hospital is a Certificate of Proficiency awarded by the Ceylon Medical College Council of Sri Lanka. All pharmacists believed that using abbreviations will always (5.3%) or sometimes (94.7%) lead to medication errors. The reasons they believed that may lead to medication errors are shown in Fig. (1). Other reasons include, the ambiguity due to incomplete prescriptions, prescriptions not conforming to a uniform standard, different styles of hand-writing used by prescribers, and the use of non-standard abbreviations formed by different prescribers which would especially be unfamiliar to junior pharmacists. All pharmacists strongly agreed or agreed that confusing or misleading abbreviations should not be used in prescriptions and all acceptable abbreviations should be standardised.

DISCUSSION

In this study we aimed to study the use of error-prone abbreviations and other inappropriately used abbreviations in prescriptions. Approximately 69 error-prone abbreviations are used per every 100 drug items prescribed. Similar to our study, Dooley et al., also observed 76.9 error-prone abbreviations per every 100 patients and 8.4 error-prone abbreviations per every 100 prescriptions [6]. Further, abbreviations are used rather inconsistently in prescriptions. A large number abbreviations used are not standard or acceptable. Some drug items or instructions are identified by several abbreviations, and some abbreviations have more than one intended meaning. An example of an abbreviation that had more than one intended meaning from this study is the abbreviation ‘d’ which was used to mean ‘days’ as well as ‘daily’. It would not be surprising if a pharmacist interpreted ‘2d’ as ‘two tablets daily’ when it was meant to read ‘one tablet for 2 days’. In such a case, the consequences to the patient, especially if the drug has a narrow therapeutic index would be significant. The use of inappropriate abbreviations may not only affect health care professionals but may cause problems to patients, particularly older patients when managing their numerous drugs [16]. Although technical abbreviations are not expected to be interpreted by patients, simple abbreviations such as the letter ‘l’ used for ‘liter’ could easily be misinterpreted as number one. Similarly, patients may misread number ‘1’ as number ‘7’, letter ‘o’ as number ‘0’, and letter ‘z’ as number ‘2’ [17]. Therefore we emphasise the importance of eliminating error-prone abbreviations and standardising the use of acceptable abbreviations as a vital necessity in hospitals that use hand-written prescriptions. Error-prone abbreviations were used in prescriptions of the study hospital but most were not identified in some of the error-prone abbreviation lists that already exist in other countries [3-5, 15]. In fact, most error-prone abbreviations

8 Current Drug Safety, 2014, Vol. 9, No. 1 Samaranayake et al.

Table 5. Demographic Characteristics of Survey Participants in the Study Hospital

Characteristic N = 18†

Age Groups, %

21 – 30 11.1

31 – 40 33.3

41 – 50 55.5

Sex, %

Men 27.8

Women 72.2

Higher Education Level*, %

Certificate of Proficiency only 88.9

Diploma in Pharmacy 22.2

Degree in other discipline 16.7

Postgraduate 5.6

Years of Experience as a Pharmacist, %

< 1 years 5.6

1– 5 years 16.7

6 – 10 years 22.2

>10 years 55.6 *Percentages do not add up to 100% as some pharmacists had more than one qualification. †Demographic data was missing in one participant. used in the study setting, were not included in the JCAHO and HAHK lists. Furthermore, many other potentially dangerous unapproved abbreviations used in prescriptions have not even been identified as error-prone. An example is the use of ‘O’ to mean ‘oral’ which could also be read as a ‘zero’. Pharmacists also pointed out that using ‘O’ is too vague as they sometimes could not differentiate between the tablet and capsule forms. Sometimes the intended meaning of an abbreviation could vary by country. For example, ‘MS’ is an error-prone abbreviation specified for ‘morphine

sulphate’ or ‘magnesium sulphate’ in the ISMP and JCAHO lists, but is used to mean ‘methyle salisylate’ in the study hospital. Hence it is clear that an error-prone abbreviation list intended for one setting is not always applicable to another. It would therefore be more prudent to develop an in-house list of error-prone abbreviations that target inappropriate practices of the respective setting. Attitudes of pharmacists are an important source to determine difficulties associated with illegible prescriptions and ambiguous abbreviations. Therefore it is very important to involve practicing pharmacists in the development of error-prone abbreviation lists. Further, awareness programs should aim at informing prescribers of the difficulties created on their account. There are some limitations to this study. Firstly the study involved only one major government hospital in Sri Lanka and hence may not reflect the overall pattern of using error-prone and other unapproved abbreviations in the country. However, this need not affect our conclusion as similar findings were observed in other studies [6] and our previous unpublished audits in Hong Kong. Secondly, our prescription sample did not include in-ward prescriptions but as in-ward doctors participate in clinics, their pattern of using abbreviations was also reflected in our findings. The inappropriate abbreviations encountered in this study and the error-prone abbreviations specified by ‘Do Not Use’ lists are in English or Latin. Abbreviations may differ depending on the language and country and hence the findings of this study may only apply to countries where prescriptions are written in English. The number of pharmacists who were attached to the outdoor pharmacy was limited. Therefore the sample of participants who were surveyed was small but included all the pharmacists in the out-patient pharmacy. A 100% response rate was achieved, but the responses may have been biased. The pharmacists were well aware of the aims and objectives of the study which may have influenced their attitudes on using unapproved abbreviations. Therefore, it must be borne in mind that the attitudes of this small group of pharmacists may not be generalisable. Care should be

Table 4. Multiple Abbreviations Used to Denote the Same Drug Name/Instruction

Drug Name or Instruction Abbreviation 1 % * Abbreviation 2 % * Abbreviation 3 %*

Diclofenac sodium DF 0.1 DFS 0.7 Diclo Na 0.1

Folic acid FA 0.5 F.acid 0.1 - -

Glyceryle trinitrate GTN 0.7 TNT 0.1 - -

Paracetamol P.mol 0.03 PCM 5.2 Par 0.03

As needed PRN 0.1 SOS 1.2 - -

Thyroxine T4 0.03 T 0.1 Thy 0.03

Microgram µg 5.1 mcg 0.03 - -

Nocte n 4.7 Nt 0.1 Noc 0.03

Methyle salicylate MS 1.9 MSLA 0.3 - -

Vesper (evening) v 0.1 ves 0.1 - - *The number of drug items observed (N=3370) was used as the denominator.

The Pattern of Abbreviation Use in Prescriptions Current Drug Safety, 2014, Vol. 9, No. 1 9

taken when interpreting the survey results until supported by more larger and representative studies. We conclude that error-prone abbreviations are used in prescriptions and more than half the abbreviations used in prescriptions are unapproved. Some drugs or instructions are identified by multiple abbreviations, while some abbreviations have several interpretations. Unfortunately, the pattern of using unapproved abbreviations by prescribers is inconsistent and changes by hospital or country. Pharmacists who are involved in interpreting prescriptions agree that this erratic use of abbreviations may lead to medication errors. Therefore hospitals that use hand-written prescriptions should inform prescribers of this danger and develop in-house error-prone abbreviations list for their guidance. Further, the use of acceptable abbreviations should be standardised by introducing a standard abbreviations list.

CONFLICT OF INTEREST

The authors confirm that this article content has no conflict of interest.

ACKNOWLEDGEMENTS

BMY Cheung received support from the Faculty Research Fund, Li Ka Shing Faculty of Medicine, University of Hong Kong. N.R. Samaranayake holds a University Postgraduate Fellowship and a Postgraduate Scholarship from the University of Hong Kong. N.R. Samaranayake also holds the Wong Ching Yee Medical Scholarship for 2012.

PATIENT CONSENT

Declared none.

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Received: October 17, 2013 Revised: December 11, 2013 Accepted: December 13, 2013 DISCLAIMER: The above article has been published in Epub (ahead of print) on the basis of the materials provided by the author. The Editorial Department reserves the right to make minor modifications for further improvement of the manuscript.

Fig. (1). Reasons why abbreviations may lead to medication errors. The percentages do not add up to 100% because each pharmacist may have suggested more than one reason.

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