Study design and settings
A descriptive, cross sectional and prospective study was conducted among patients attending out-patients pharmacies in a selected teaching hospital (study hospital pharmacies) and a selected community pharmacy (study community pharmacy) in the Colombo district. Although, the study settings were selected through convenience sampling, the study hospital is one of the main tertiary care hospitals in Sri Lanka, and the community pharmacy is an outlet of the only state owned pharmacy chain in Sri Lanka.
The study hospital is a tertiary care hospital with a bed strength of 1099 and approximately 40 different types of functioning outpatient clinics. There are three out-patient pharmacies to serve patients who attend these clinics. Medicines are dispensed to around 2100 clinic and other out-patients through these pharmacies per day. The study community pharmacy is one outlet of the state owned community pharmacy chain, and serves around 600 patients a day.
In Sri Lanka, essential dosing instructions are provided to patients by the pharmacist in written form based on the prescription provided by the prescriber. The common practice is to have pre-semi-printed labels on medicine envelopes which will be used for packing medicines. The semi-printed label includes, typed sentences of dosing instructions, with blank spaces to fill the information which varies with the type of medication. Sometimes, the printed forms are not available and pharmacists use the face of the blank envelope to write dosing instructions.
Study participants
Participants were included in the study if, they were patients or caregivers over 18 years of age, who could speak and understand Sinhala and/or English language, and were dispensed at least one medication from study pharmacies. Those who were illiterate, disabled, diagnosed with psychiatric disorders, dispensed only surgical/medical devices, or dispensed only external preparations were not selected.
Sample size calculation and sample selection
The number of participants were calculated separately for hospital and community settings using an online sample size calculator (Raosoft. Inc) and considering 95% confidence level, 5% significance, and a response distribution of 50%. A minimum sample size of 384 participants was calculated for each setting, and 400 participants were selected from each setting (N = 800) after anticipating a drop-out rate of 10%.
A systematic random sampling technique was used to select study participants. Every 5th patient/caregiver who attended the study setting during a specified time on weekdays, and fulfilled the inclusion criteria, were selected for the study until the minimum sample size (400 from each setting) was achieved. If a participant did not consent to take part or did not fulfill the inclusion criteria, the next patient according to the systematic sampling technique was approached.
Data collection and scoring procedure
Data were collected by two research pharmacists during a period of 2 months using a pre-determined data collection form (Additional file 1). The two researchers were trained on the data collection process, and both were engaged in collecting data from one patient at a time to minimize inter-researcher variability in data collection. The two researchers approached the patient to be selected, and explained the study process.
Assessing the completeness of written dosing instructions
A list of essential dosing instructions that should essentially be provided with dispensed medication were compiled by researchers using the ‘Guidelines for Dispensing of Medicines Developed by Pharmacy Board of Australia’ [23], Prescription Drug Products Labeling; Medication Guide Requirement [24] and WHO Good Dispensing Practices [25], and the list was further endorsed by three pharmacy experts in Sri Lanka.
The two researchers observed if these essential dosing instructions were written on each dispensing label. A score of one was awarded for each dosing instruction written on the dispensing label, and was summed up to obtain a total score for ‘completeness’ of dosing instructions for each dispensing label/medication. The total scores were converted to a score out of 10, using the following formula for ease of comparison.
$$ \mathrm{Score}\ \mathrm{out}\ \mathrm{of}\ 10\ \mathrm{for}\ \mathrm{completeness}\ \mathrm{of}\kern0.50em \mathrm{dosing}\ \mathrm{instructions}\kern0.5em \mathrm{for}\ \mathrm{a}\ \mathrm{medication}=\frac{\mathrm{Number}\ \mathrm{of}\ \mathrm{correctly}\ \mathrm{written}\ \mathrm{dosing}\ \mathrm{instructions}\ \mathrm{per}\ \mathrm{medication}}{\mathrm{Number}\ \mathrm{of}\ \mathrm{dosing}\ \mathrm{instructions}\ \mathrm{that}\ \mathrm{should}\ \mathrm{be}\ \mathrm{written}\ \mathrm{by}\ \mathrm{the}\ \mathrm{pharmacist}\ \mathrm{for}\ \mathrm{the}\ \mathrm{type}\ \mathrm{of}\ \mathrm{medication}\ \mathrm{dispensed}}\mathrm{x}\ 10 $$
An incomplete dosing instruction included, essential dosing instructions missing in dispensing labels, use of unapproved abbreviations to define medicine names or any other dosing instruction, and use of illegible instructions, difficult for researchers to read or interpret. Both printed and handwritten forms of instructions were considered appropriate and adequate. Even a brand name mentioned with no clear indication of a generic name was considered complete, especially in the case of combination products (E.g. Multivitamins, Omega-3-fatty acids). Special instructions were only considered essential depending on the type of medicine.
Assessing the readability of dosing instructions
The researchers asked the patient to read each written or printed dosing instruction on the dispensing label of each medicine. Dosing instructions were categorized as readable if patients were able to correctly and completely read the instructions without any assistance. Each correctly read instruction was awarded a score of one. Incompletely or incorrectly read instructions were scored zero. The total score for ‘readability of dosing instructions’, for each medication, was converted to a score out of 10 using the following formula.
$$ \mathrm{Score}\ \mathrm{out}\ \mathrm{of}\ 10\ \mathrm{for}\ \mathrm{read}\mathrm{a}\mathrm{bility}\ \mathrm{of}\kern0.50em \mathrm{dosing}\ \mathrm{instructions}\ \mathrm{for}\ \mathrm{a}\ \mathrm{medication}=\frac{\mathrm{Number}\ \mathrm{of}\ \mathrm{correctly}\ \mathrm{read}\ \mathrm{dosing}\ \mathrm{instructions}\ \mathrm{per}\ \mathrm{medication}}{\mathrm{Number}\ \mathrm{of}\ \mathrm{dosing}\ \mathrm{instructions}\ \mathrm{written}\ \mathrm{by}\ \mathrm{the}\ \mathrm{pharmacist}\ \mathrm{for}\ \mathrm{the}\ \mathrm{type}\ \mathrm{of}\ \mathrm{medication}\ \mathrm{dispensed}}\mathrm{x}\kern0.5em 10 $$
Assessing the knowledge on dosing instructions
Researchers asked patients a predetermined set of questions related to essential dosing instructions of each dispensed medication to verify patients’ understanding on the same. The questionnaire assessed patients knowledge on the name, dosage form, strength, number of units taken at a time, route of administration, frequency of administration, time of taking medicines (before or after meals) related to the medicines they take. The assessment questions were endorsed by three pharmacy experts for appropriateness before data collection. Patients were given a score of one, for each correctly answered question. The total score for ‘knowledge of dosing instruction’ for each medication, was converted to a score out of 10 using the following formula.
$$ \mathrm{Score}\ \mathrm{out}\ \mathrm{of}\ 10\ \mathrm{for}\ \mathrm{knowledge}\ \mathrm{of}\kern0.50em \mathrm{dosing}\ \mathrm{instructions}\ \mathrm{for}\ \mathrm{a}\ \mathrm{medication}=\frac{\mathrm{Number}\ \mathrm{of}\ \mathrm{correctly}\ \mathrm{interpreted}\ \mathrm{dosing}\ \mathrm{instructions}\ \mathrm{per}\ \mathrm{medication}}{\mathrm{Number}\ \mathrm{of}\ \mathrm{dosing}\ \mathrm{instructions}\ \mathrm{that}\ \mathrm{should}\ \mathrm{be}\ \mathrm{written}\ \mathrm{by}\ \mathrm{the}\ \mathrm{pharmacist}\ \mathrm{for}\ \mathrm{the}\ \mathrm{type}\ \mathrm{of}\ \mathrm{medication}\ \mathrm{dispensed}}\mathrm{x}\kern0.5em 10 $$
In addition to, incorrect and incomplete responses and failing to respond to questions, a patient interpreting a medicine strength without units or using incorrect units, and interpreting the duration of medicines as ‘a month’ for a 28 day/4 week supply of medicines were also considered incorrect.
Statistical analysis
Statistical Package for the Social Sciences (SPSS) version 21 was used for data analysis. The total number of medicines dispensed among study participants was used as the denominator for calculating percentages in each setting. Chi square analysis was used to determine relationships between categorical variables. Mann-Whitney-U test and Kruskal Wallis test were used to compare means. A 5% significance level was used when determining P values. Participants with missing data were excluded from the analysis.
Ethical consideration
Patient identifiers were not used when collecting data, and the data sheets were only accessible to investigators. If a serious medication error was detected, the researchers were trained to contact the principle investigator immediately. The principle investigator, upon verifying the error, was to report to the practicing pharmacist regarding this negligence. Direct communication by researchers regarding the quality of medication dispensing was discouraged.