ABSTRACT The fact that today&apos;s evidence based guidelines recommends several drugs in the treatment of a single medical condition make drug treatment particularly challenging. Consequently, many patients use a number of medications a situation referred to as polypharmacy. Polypharmacy is linked to occurrence of health risk through increased drug therapy problems like adverse drug reactions, medication error, adherence problem, economic burden etc. This study characterized the quality of out-patient prescriptions in National Health Insurance Scheme (NHIS) of the University of Maiduguri Teaching Hospital, using some selected indicators of Polypharmacy. These include contraindication, drug interaction, drug for treating side effect of co-prescribed drug and inappropriate dosages. Five Hundred out-patient prescriptions were used for the study. The average number of drug per prescription was 3.95±1.51. About 20.4% of the encounter received prescription with inappropriate combination of five or more drugs. Of this, contraindicated drugs constituted 22.2% of all encounter. There was association between inappropriate prescription and number of drug per prescription (p&lt;0.05). The incidence of inappropriate prescription, potential drug therapy problems, and inappropriate polypharmacy were significantly higher at drug level ≥5 drugs. There is the need to improve on rational prescribing of drugs by retraining of health care providers

* J Muazu

A Abubakar

G U Sadiq

N Y Ikunaiye

S Y Zarma

Y H Umar

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January – March          2010               RJPBCS            Volume 1 Issue 1              Page No.57
Research Journal of Pharmaceutical, Biological and Chemical 
Sciences
Assessment of Quality of Out-patient Prescriptions in the National Health 
Insurance Scheme Unit of a Tertiary Hospital in Nigeria
*J Muazu1, NY Ikunaiye1, A Abubakar1, GU Sadiq2, SY Zarma1 and YH Umar1
1Department of Pharmaceutical Services, University Of Maiduguri Teaching hospital. 
1Department of Ethnopharmacy and Drug Development, University of Maiduguri.
ABSTRACT
The fact that today's evidence based guidelines recommends several drugs in the treatment of a 
single medical condition make drug treatment particularly challenging. Consequently, many patients use a 
number of medications a situation referred to as polypharmacy. Polypharmacy is linked to occurrence of 
health risk through increased drug therapy problems like adverse drug reactions, medication error, adherence 
problem, economic burden etc. This study characterized the quality of out-patient prescriptions in National 
Health Insurance Scheme (NHIS) of the University of Maiduguri Teaching Hospital, using some selected 
indicators of Polypharmacy.  These include contraindication, drug interaction, drug for treating side effect of 
co-prescribed drug and inappropriate dosages. Five Hundred out-patient prescriptions were used for the 
study. The average number of drug per prescription was 3.95±1.51. About 20.4% of the encounter received 
prescription with inappropriate combination of five or more drugs. Of this, contraindicated drugs constituted 
22.2% of all encounter. There was association between inappropriate prescription and number of drug per 
prescription (p<0.05). The incidence of inappropriate prescription, potential drug therapy problems, and 
inappropriate polypharmacy were significantly higher at drug level ≥5 drugs. There is the need to improve on 
rational prescribing of drugs by retraining of health care providers.
Keywords: Polypharmacy, selected indicators, drug therapy problems, prescribing.
*Corresponding author
Tel: +234 803 743 9543
Email: jmuazu@gmail.com
January – March          2010               RJPBCS            Volume 1 Issue 1              Page No.58
INTRODUCTION
Polypharmacy refers to the use of several medications concurrently in single individual. However, 
definitions vary in the minimum number of drugs used by patients concomitantly. In the elderly, polypharmacy 
is usually defined as the use of more than three or four medication [1]. Kingsbury et al [2] defined 
polypharmacy as the use of two or more medication to treat the same condition, use of two or more drugs of 
the same chemical class or use of two or more drugs with similar pharmacologic actions to treat different 
conditions.High frequency of polypharmacy was reported in literature in the treatment of serious illness [3, 4],
elderly [5, 6] chronic diseases [2] and rheumatic diseases [7]. Although there are rational and irrational 
polypharmacy, use of multiple drugs may increase adverse drug event (ADE), drug interaction, medication 
error, and patient non-adherence and elevated mortality rate [8].  These possible heightened health risk 
occasioned by polypharmacy are usually compounded if the patient is also taking herbal preparations.  Reports 
have shown that 80% of adult in Africa use one or more herbal preparation for treatment [9]. Polypharmacy,
as commonly limited to number of drug, has limited value in measure of quality of prescription, it was
advocated that the need to separate rational polypharmacy from irrational polypharmacy as rational 
polypharmacy is considered as a veritable tool in the management of illnesses such as hypertension, cancer, 
etc. In separating irrational polypharmacy from rational one some indicators/predictors of irrational 
polypharmacy beyond the number of drug per prescription have been identified to include presence of 
contraindicated drug, un-indicated drug, duplicated drug in the same category, inappropriate drug interaction, 
wrong dosages, and drug prescribed for treatment of side effect of co-prescribed drugs[10].This study used 
some of these indicators to analyse out-patient prescription in National Health Insurance Scheme(NHIS) unit of 
University of Maiduguri Teaching Hospital, Nigeria.
METHODOLOGY
This was a retrospective study that involved the use of prescription filled and stored at the NHIS 
pharmacy from the period of January to August, 2009.
Sample size
The out-patient prescription from January- August 2009 was used. The total number of prescription 
was ten thousand five hundred and forty.
- For sample frame ≥10,000
Where, 
N= desired sample size
z= standard normal deviate (1.96)
p=proportion in the target population which have a particular characteristics (50% in absence of reasonable 
estimate i.e. 0.5)
q=1-p (0.5)
d= degree of accuracy usually at 0.05
                N= 384
To increase the power of the research and possibly to accommodate analysis like cross-tabulation, 
this calculated sample size was increase to 500. Five hundred out-patient prescriptions were randomly 
selected from the pool of 10,540 prescriptions for the period of study. It was a multi step process, 2000 
prescriptions were randomly picked from the pool and numbered 1-2000. Using a Biostat, statistical software, 
500 random numbers were generated between 1 and 2000. Five hundred prescriptions were then picked 
January – March          2010               RJPBCS            Volume 1 Issue 1              Page No.59
corresponding to the generated numbers for the analysis. Other data such as patient history, 
diagnosis/impression for the selected prescription were then obtained from NHIS database. Number of drug(s)
per prescription was recorded and each prescription compared with the patient history, diagnoses/impression 
for any indicators of polypharmacy. Score zero (0) was assigned for absence of each indicator and score one (1) 
for presence of each indicator. Sum of scores of the indicators per prescription was also recorded.  The analysis 
of data was carried out using SPSS 15.
RESULT AND DISCUSSION
The distribution of males and females were 38.8% and 61.2% respectively. The population aged less 
than 40 years constituted the majority (59.6%) and those greater than 40 years was 11%. The remaining 29.4% 
of the prescriptions has no age on both prescription and the database, the ages were simply written as 'ad' 
signifying adult. Number of drugs per prescription was shown in figure 1, the minimum and maximum number 
of drugs per prescription was 1 and 8 respectively. The least encountered prescriptions were those containing 
8 drugs (0.8%) while the highest was prescriptions containing 4 drugs (23.8%). The average number of drug per 
prescription ± for all encounter was 3.95±1.51 (2.44 - 4.46) which is consistent with the figure of 3.7 obtained 
at the central hospital, Benin- City [11] and that obtained (3.2-3.3) in paediatric hospital in Ethiopia but well
above the WHO target of 2.0 [12].   Considering WHO indicators for good prescription, this average number of 
drug per prescription is   high and it could be as a result of treatment based on symptoms without definitive 
diagnosis and lack of or non-conformity to treatment guidelines in health facilities. In the case of NHIS clinic it 
could have been due either to noncompliance to the scheme treatment protocol or ill implementation of drug 
use guidelines of the scheme. It might also be as a result of pressure from patient to prescribe other drugs as 
patients usually pay only 10% of the cost of drugs.
number of drug(s) per prescription
8.007.006.005.004.003.002.001.00
P
e
r
c
e
n
t
25
20
15
10
5
0
0.8
3.2
12.8
19.2
23.8
21.6
14.8
3.8
Fig1: The percentage number of drug(s) per prescription.
The contribution of each indicator for polypharmacy was shown in figure 2. The most practised indicator for 
polypharmacy is contraindication and the least practised is drugs prescribed to treat side effect.
indicators of polypharmacy
interaction
inappropriate dosage
drug prescribed for
duplicated drug
containdication
p
e
r
c
e
n
t
a
g
e
 
b
y
 
p
r
a
c
t
i
c
e
 
o
f
 
i
n
d
i
c
a
t
o
r
25.00
20.00
15.00
10.00
5.00
0.00
4.80
2.00
8.20
22.20
0.4
Fig 2: Polypharmacy indicators practice profile
January – March          2010               RJPBCS            Volume 1 Issue 1              Page No.60
Inappropriate prescriptions (33%) account for prescriptions which have at least one of the indicators of 
polypharmacy irrespective of the number of drugs per prescription. Appropriate prescription (67%) showed
prescriptions without implicated indicators as shown in figure 3.
appropriate prescription
inappropriate presc.
Yes
No
Percent
6040200
67
33
a propriat  p escr.
inappropriate prescr.
Fig 3: The frequency of appropriate and inappropriate prescription
polypharmacy status
YesNo
F
re
q
u
e
n
cy
400
300
200
100
0
polypharmacy status
20.4% 
polypharmacy
79.6% free of 
polypharmacy
Fig 4: Polypharmacy status of prescriptions in NHIS, UMTH
Polypharmacy occurred in 20.4% of the prescriptions, i.e the prescriptions contained 5 or more drugs and at 
least one implicated indicators of polypharmacy. Contraindicated drugs constituted 22.2% of all encounter. 
This study considered inappropriate drug-disease interaction under contraindication. This observed drug 
interaction is comparable to other studies in primary health care that reported 24% of potential drug 
interaction for patient expose to polypharmacy [10]. Contraindication contributed most to the inappropriate 
polypharmacy and was high due to inclusion of unindicted drugs on the prescription.
The relationship between inappropriate prescription and number of drugs per prescription was 
shown in figure 5. The curve showed that increase in number of drugs lead to increased chances of 
inappropriate prescription. As observed the prescription with the highest number of drugs (8) has 100% 
chances of being inappropriate.
The cross-tabulation of incidence of inappropriate prescription with numbers of drugs per 
prescription which was subjected to Chi square test show some level of association between these two 
variables that was statistically significant (p<0.05). To determine the strength of association between them, 
they were also correlated using Pearson correlation analysis which confirmed the association to be positively 
related (p<0.05).  Inappropriate polypharmacy and potential drug therapeutic problems showed strong 
positive correlation with the number of drug per prescription. 
January – March          2010               RJPBCS            Volume 1 Issue 1              Page No.61
number of drug per prescription
87654321
M
e
a
n
 
i
n
c
i
d
e
n
c
e
(
p
e
r
c
e
n
t
a
g
e
)
 
o
f
 
i
n
a
p
p
r
o
p
r
i
a
t
e
 
p
r
e
s
c
r
i
p
t
i
o
n
100.00
80.00
60.00
40.00
20.00
0.00
100.00
87.50
60.90
49.00
29.40
18.50
8.10
0.00
inapropriate prescription vs number of drug per 
prescription
Fig 5: Incidence of inappropriate prescription with number of drugs per prescription
Post hoc ANOVA showed that the incidence of inappropriate prescription, and potential drug related 
problems which correspond with the sum of scores of all indicators per prescription were significantly higher 
at drug level ≥5drug when compare with the other drug level (0-1 and 2-4drug). This is consistent with other 
pharmacoepidemiological studies that have shown number of drug per prescription as a strong predictor of 
these variables [10]. Linear regression analysis showed that all the indicators contributed to polypharmacy 
practice in NHIS. Drug prescribed for side effect was a weak independent factor for polypharmacy in this study 
area.   
CONCLUSION
Despite this study discrimination among rational and irrational polypharmacy, the incidence of the PP
was high (20.4%). Inappropriate prescriptions and chances of drug therapeutic problems vary directly with the 
number of drugs per prescriptions and the variance is more pronounced with prescriptions with 5 or more 
drugs.
On this note, the quality of prescriptions can be improved and potential DTPs reduced if the 
physicians, the pharmacists ensure that the choice of drug for the patient is based on indication and safety by 
avoiding potentially dangerous combination with proper attention to these indicators of polypharmacy.
Strict compliance to and proper implementation of treatment guidelines is imperative to improving 
quality of prescription. Drug and therapeutic committee and drug information centre need to be established 
and utilised in our various clinics.
REFERENCES
[1] Ziere G. Dieleman SP, Hofman A, Pols HAP, van der Cammen TJM, Sticker BHC.  British J. Clin.
Pharmacol. 2005; 61: 218-223.
[2] Kingsbury SJ, Yi D, Simpson GM. Psychopharmacol 2001; 52: 1033-1035.
[3] Williams CL, Johnstone BM, Kesterson JG, Javor KA, Schmetzer AD. Med. care 1999; 37: 81-86.
[4] Frye MA, Ketter TA, Leverich GS, Huggins T, Lantz C. J. Clin. Psy.200; 61:9-15.
[5] Buckley BM. Eur Heart J. 2001; 3: 6-10.
[6] Fulton MM, Allen ER, J Am Acad Nurse Pract.2005; 17:123–132.
[7] Viktil KK, Enstad M, Kutschera J, Smedstad LM, Schjott H. Pharmacy World Sci. 2001; 23:153–158.
[8] Waddington JL, Youssef HA, Kinsella A. British J. Psy. 1998; 173: 325 - 329
[9] Muazu J, Kaita AH. Afr. J. Trad, CAM 2008; 5: 387-390.
[10] Bjerrum L, Rosholm JU, Hallas J, Kragstrup J. Eur J. clin. Pharmacol. 1998; 53: 7-11.
[11] Isah AO, Ohaji-Obodo J, Isah EC, Ozemoya O. Pharmacoepidemiology and drug safety. 1998; 11: 922 –
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Assessment of Quality of Out-patient Prescriptions in the National Health Insurance Scheme Unit of a Tertiary Hospital in Nigeria

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Assessment of Quality of Out-patient Prescriptions in the National Health Insurance Scheme Unit of a Tertiary Hospital in Nigeria

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