Europ. J. clin. Pharmacol. 12, 31-35 (1977) European Journal of Clinical Pharmacology © by Springer-Verlag 1977

Recording of Drug Prescriptions in the County of J imtland, Sweden

I. Methodological Aspects

G. Boethius, and F. Wiman

Department of Medicine and Hospital Pharmacy, Ostersunds Hospital, Ostersund, and Department of Clinical Pharmacology at Karolinska Institutet, Huddinge University Hospital, Huddinge, Sweden

Summary. Prescribed drugs dispensed to 13% (17 000) of the inhabitants in the county of J~imtland, Sweden, have been continuously recorded since 1970. Individual patients in the investigation are fully identi- fiable by their identity number as used in Sweden, so patients exposed to a particular drug or group of drugs can be reached subsequently, e. g.~ for studies of the incidence and nature of side effects. The following information is coded at the local pharmacies: prescrib- ing physician, dispensing pharmacy, year and week of dispensation, name, amount and price of drug, dos- age, type of prescription record. In a five year period the drop-out rate has decreased from 9% in 1970 to 4% in 1974. Every year at least one drug is prescribed for approximately 60% of the population. During the five year period 74% of the male and 80% of the female population purchased prescription drugs. The representative nature of the data is discussed, as welt as their value in detection of irrational drug usage and ascertaining any particular patient's drug history.

Key words: Prescriptions, drug exposure, phar- macotherapy, surveillance, methodology, side effects.

Before a new drug is introduced on the market drug control agencies thoroughly examine its toxicological profile in animals and man, as well as its clinical effica- cy. Nevertheless apparently safe medicines may still produce serious side-effects, which are detected at a later stage of drug evaluation when more patients have been exposed to the drug for sufficiently long periods of time. With this perspective it is of interest to public health authorities to be able to identify a popu- lation at risk whenever suspicions arise about new side

effects. One way to achieve this is to record all drug prescriptions in representative and identifiable sam- ples of the population. So far, most studies of drug usage have dealt with gross sales- or prescription fig- ures, or individual use over short periods of time. Long term studies of a large number of individuals have not been done, mainly because of methodologi- cal difficulties [1].

In order to analyse continuously the pattern of drug use on an individual basis, in 1968 registration of outpatient prescriptions was initiated in the county of J/imtland, Sweden [2]. A pilot study over 16 months involving 3000 individuals has gradually been ex- tended and the method of collecting information has been further developed. The purpose of this report is to describe the methodology involved and briefly to discuss potential uses of the data.

Material and Method

In 1970 the county of J~mtland (Fig. 1) had a popula- tion of 125 720. In 1973 the border was extended to take in three additional parishes, including one phar- macy, at the north eastern border of the county, which increased the population to 132 793 (1974). This part was not included in the prescription records until 1975.

The county hospital in Ostersund dominates the health service. In it work approximately 125 hospital physicians representing 18 specialties. There are a- bout 40 physicians in the various districts, and a dozen private practitioners. Outpatient visits yearly to these three categories of physicians approximate 150000 160000 and 25 000 visits, respectively.

Outpatient prescriptions dispensed to individuals born on the same four days in each month are included in the study; in this way 4/30 (13%) of the population,

32 G. Boethius and F. Wiman: Recording Prescriptions

/

0

Fig. 1. The county of Jiimtland in the middle of Sweden. Four pharmacies (A) are located in the town of Ostersund

or approximately 16 600 persons (from 1975 17 500), are under continuous study. All 19 pharmacies in the county, including the sole hospital pharmacy, collect information from 70-80 000 prescriptions every year. Requisitions for drugs for doctors' and dbntists' of- rices, veterinary prescriptions and prescriptions not entitled to price deduction, i. e. drugs costing less than 5 Sw. crowns and drugs for prophylactic use, are ex- cluded; they amount to 6% of the total number.

Using an optical character reading (OCR) tech- nique the following data are recorded: Identity Number: all individuals in Sweden are fully identifiable by an identity number, which consists of date of birth (year-month-day, six digits), place of birth and sex (three digits) and finally a control digit. Year and Week: when dispensed. Prescribing Physician (or dentist): coded by speciality and position, but not as an individual. Pharmacy: where prescription is dispensed. Article Number: a nationwide code system indicating strength and quantity of each drug pack available in the country. When retrieving data price, quantity, brand name and strength of the dispensed drug are given. For extemporaneous preparations a special code is used according to type of preparation - mix- ture, ointment etc.

Dosage: a 2-digit (from 1975 3-digit) code has been designed. Type of Prescription Form: original, redispensed, by telephone, drug free of charge, drug entitled to price deduction etc.

The information on the prescription is coded on an OCR form (Fig. 2) at the local pharmacy. The date of birth on the prescription is converted to the identity number with supplementary information from the population register of J/imtland county. This is done by special personnel at the county hospital. In this way tourists and others not resident in the county are ex- cluded from the study as non-identifiable individuals.

The information has been processed so far once or twice yearly, and retrieved in the form of print-outs of drugs dispensed to each individual, in chronological or pharmacological order. A number of programs have been designed for special analyses.

Results

The number of prescriptions dispensed in the county is about the same every year and amounts to 1.5% of that in the entire country (Table 1). Prescriptions not coded have decreased during the period as better in- formation has become available to the personnel at the pharmacies, and they now amount only to a few per cent. The degree of faulty coding has been small and the essential information has been corrected. Of the coded prescriptions 8-11% have been dispensed to non-identifiable individuals, i.e. persons not in the census list. Using in- and outpatient medical records in a thorough investigation in 1973 of a sample of such non-identifiable prescriptions, it was found that one fourth of them actually belonged to county residents. These prescriptions, together with those not being coded at all (Table 1), make up a total drop-out of approximately 9, 7, 7, 4 and 4%, respectively, for the years studied.

As the rate of coding has improved, the number of drug purchasers has increased, to approach the true figure. Every year at least one drug is prescribed for approximately 60% of the population (Table 2). Since the population has changed during the observation period 1970-74, because of births, deaths and migra- tion, the exact proportion that has received at least one prescribed drug in the five years is difficult to state. An estimate has been made, considering all people (151590) who have resided in the county dur- ing the period, regardless of duration, as potential purchasers; 74% of the men and 80% of the women have obtained prescribed drugs in the five year period. Their age and sex distribution is shown in Figure 3.

The ten most frequently dispensed drug groups in

G. Boethius and F, Wiman: Recording Prescriptions 33

N Apoteksbolaget

I

Pleosewrite the digits like this^ The .Idmtlcmd study

Name ol palient ]

Pharmacy gear Week Pallent's idenldy number 1

S~Nf]N DN [iN N~DD~N DD~D I" ikrlscl ~ number C!uontil i Bosoqe Prescrlption fQrlrm Price Physlclon code l

1D~@SN~ NND NNN N UNN IN~EIlZ]N 2N@DDNN D@D @ND S ~NN @DD~N

~N~DD~N NND @NN @ ~NN S@D@N ~D@DD~N NOD SDN D @N~ NND~N oDSSNNN SNS NNN S ~NN NSNSN

Fig. 2. OCR form (Optical Character Reading) in use since 1975

Table 1. Coded prescriptions compared to those dispensed in the county of J~imtland; figures come from the 13% sample of the population

1970 1971 1972 1973 1974

Prescriptions dispensed in county" 70107 71227 69 825 70743 76938 coded 64 942 67 735 67 245 69 394 74 840 % not coded 7.4 4,9 3.7 1.9 2.7 fully identifiable (prescribed to county residents) 59961 60 766 59 908 63 506 68 785 % of coded 92 90 89 92 92

a Excluding the 6% not recorded in this study: requisitions for drugs to doctors' offices, veterinary prescriptions and prescriptions not entitled to price deduction (see text).

Table 2. Recorded drug purchasers in relation to the population of the J~imttand county. The figures come from the 13% sample of the population

1970 1971 1972 1973 1974

monitored county population 16 542 16525 16605 16 663 16728 individuals recorded as purchasers 11291 12345 12 845 12 601 13 050 individuals identifiable as county 9337 9445 9436 9872 10305 residents

Table 3. The ten most frequently dispensed groups of drugs in 1973

Identified group of patients (n = 9 872) Non-identified group of patients (n = 2957) Drug % of patients Drug % of patients

Antipyretic analgesics 28.4 Antibiotics 16.5 Antibiotics 26.2 Antipyretic analgesics 14.5 Hypnotics, sedatives 21.9 Hypnotics, sedatives 14.2 Antihistamines 12.9 Antihistamines 6.8 Multivitamins 12.5 Bronchial dilators 6.1 Corticosteroid ointments 11. I Anticholinergics 6.0 Diuretics t 0.8 Multivitamins 5.9 Anticholinergics 10.7 Diuretics 5.2 Nasal decongestants t 0.4 Nasal decongestants 5.1 Bronchial dilators 8.8 Cardiac glycosides 4.7

34 G. Boethius and F. Wiman: Recording Prescriptions

1°° I ~- 80~-

N 60 i X ~6 40

20

0L 0 t; 2; 3; 6? 9 19 29 39 s9

7; 8; e 79

Fig. 3. Percentage of population obtaining prescribed drugs in one year (1974). The extent of each bar indicates the proportion of the population receiving one or more drugs in the five year period 1970-74

1973 are listed in Table 3. Among county residents, antipyretic analgesics, antibiotics and hypnotics-seda- tives were predominant; and in the non-identified group, antibiotics topped the list, closely followed by the other two groups.

Discussion

The county of J~imtIand in the middle of Sweden is rich in forests and mountains and has small agricultural areas. There are a limited number of industries of small to medium size, mostly in the central part. The mountains are popular with summer and winter tour- ists. In spite of an unemployment rate exceeding the average in the country, the population is quite stable and amounts to 1.5% of the total number of people in Sweden. About 6% move into or out of the county every year; the corresponding figure for urban areas in Sweden is 7-9%. The area of the county corresponds amounts to 11% of the Swedish land area and the population density is therefore quite low. Other fac- tors may also influence the representative nature of the prescription data. The proportion of older people, of unmarried people and of non-wage earners is 4-5% higher in Jfimtland than in Sweden as a whole [3].

Since extensive analyses of the data have not been carried out until the past two years, relatively little information about the investigation has been given to the physicians in the county. A feed-back mechanism influencing their prescribing habits and thereby the representativeness of the data so far appears improb- able. Physicians have not been found to evade the four birthdays for which data is recorded, nor is there any reason to suspect that patients, who might know of or have a negative attitude towards the registration sys-

tem, have their prescriptions dispensed outside the county. A small number of persons, living near the county border get their drugs from outside because of better means of transportation. The number of pre- scriptions filled in pharmacies in other parts of Swe- den by county residents on vacation, for instance, is not known.

The drug pattern in the identified and non-iden- tified groups has been quite similar (Table 3). Within the latter one might expect a high proportion of drugs used in acute illnesses, e.g. antibiotics, analgesics, an- tihistamines and bronchial dilators. The presence on the list of more chronic medications, such as diuretics and cardiac glycosides, is due to the fact that one fourth of the non-identified prescriptions in 1973 ac- tually belonged to county residents. The high propor- tion of hypnotics-sedatives can be accounted for in the same way. In the identified group 1-2% of the indi- viduals received prescriptions from physicians outside the county, whereas 15-20% of the non-identified persons presented such prescriptions.

In the pilot study all information was coded cen- trally by a punch card technique. In order to simplify the collection of information, reduce costs and speed up processing, coding was later decentralised to local pharmacies and an OCR technique was introduced. Due to the discussion about personal integrity in com- puter-based information systems, the identity number of the patient was replaced by date of birth, sex and initial letters of family and Christian names, but this lower level of identification made the material too heterogeneous. The changing of names through mar- riage, more than one Christian name being used etc., made coding of initial letters inexact. Tourists and others not resident in the county also became included in the study. As the essential idea of individual regis- tration of a defined population was lost, the identity number had to be employed again in the investigation.

Outpatient prescription recording has been car- ried out in the last decade by several workers. The level of identification of the individual patient varies with the purpose of the surveillance, and with the existing identification system used in the country. In Prague [4] and Reykjavik [5] an identity number simi- lar to the Swedish one has been used, whereas East German data [6] include name, year of birth, sex and address of patient. McEvilla [7] used patient identifi- cation either by name or assigned number and claimed that complete, continuous drug profiles could be ob- tained. Regardless of the method employed, longitu- dinal investigations call for absolute identification of the individuals studied. The identity number used in Sweden seems to fulfill this demand.

The continuous recording of drug prescriptions in

G. Boethius and F. Wiman: Recording Prescriptions 35

identified individuals has a number of potential appli- cations, especially in areas where other methods of drug surveillance provide limited information [8, 9]:

Late adverse effects of drugs. Reports from three dif- ferent research groups on a suspected link between long-term treatment with reserpine and breast cancer, albeit not confirmed, emphasize the importance of this issue. Selection procedures and other method- ological difficulties in such studies have been much discussed. In our data, individuals exposed to a certain drug or group of drugs can easily be identified, either for immediate check up, or for surveillance, in order to reveal negative and positive effects of (long-term) treatment as early as possible. Itospital discharge diagnoses of an exposed group of individuals may be continuously followed, but outpatient diagnoses are generally not so easily obtained.

tained by data processing are subject to a licensing procedure by the Data Inspection Board [12]. The Board has approved the project whilst the data col- lected so far is evaluated. The future of our registra- tion system relies on the final decision of the Board and on the results of the present evaluation.

Acknowledgements. The valuable advice given by Drs. I. Bergstr6m, P.-A. Heedman, and B. K~illstr6m, Ostersund, is gratefully acknowledged. We wish also to thank Prof. E. Allander, Dept. of Social Medicine, Huddinge University Hospital, for revising the man- uscript. The project is sponsored by grants from the National Corporation of Swedish Pharmacies and the County Council of J/imtland.

References

The incidence of misuse or overuse of different drug categories, for example hypnotics and sedatives, may be estimated [10]. Furthermore, knowledge of the incidence of irrational drug utilization by physicians, such as overprescribing, inadequate dosage and pre- scription of interacting drugs, may serve as an impetus for training programmes in pharmacotherapy.

The reliability of the drug history in hospital and out- patient medical records is being investigated. In a pilot study Bergstr6m et al. [2] found full agreement be- tween inpatient records and prescription data in only 12 out of 20 patients. Drug-induced disorders are not uncommon; a reliable drug histoI2¢ may lead more quickly to the proper diagnosis in these cases.

The rate of prescription compliance m different patient categories and in chronic disease is largely unknown. Our data may answer questions such as how many individuals with hypertension regularly present their prescriptions [11]?

The effect of drug regulations, recommendations and sales promotion efforts on the prescribing pattern may be measured and evaluated.

In recent years growing concern and discussion about the protection of privacy has focussed on the need to balance conflicting interests, in particular the discre- pancy between privacy and integrity of the individual and the demands for rational and effective use of computer technology for recording, processing, stor- age and retrieval of information. In accordance with the Swedish Data Act of 1973, all personal files main-

1. Rabin, D. L., Bush, P. J.: The use of medicines: historical trends and international comparisons. Int. J. Hlth Serv. 4, 61-87 (1974)

2. Bergstr6m, I., Carmstad, A., Elwin, C.-E., Heedman, P.-A., Kiillstr6m, B., Mo611, B., Swar~n, U., Westerholm, B., Wiman, F.: Prescription recording in the county of J~mtland. Lfikartid- ningen 67 (Suppl. I) 38-45 and (Suppl. III) 91-99 (1970)

3. Statistical abstract of Sweden 1970--74. Stockholm: The Na- tional central Bureau of Statistics 1974

4. Stika, L., Hovorova, M., Kratochvil, J.: Automated processing of medical prescriptions. Activ. nerv. sup. (Praha) 13, 228-229 (1971)

5. Grimsson, A., Olafsson, O.: Drug prescription in Iceland. To be published.

6. Bretschneider, K., Voss, H.: Rezeptauswertung durch ma- schinelle Datenverarbeitung. Z. firztl. Fortbild. (Berl.) 64, 405-412 (1970)

7. McEvilla, J. D.: A computerized prescription recording system. J. Amer. pharm. Ass. NS 7, 636-638 (1967)

8. Jick, H.: Drugs - remarkably nontoxic. New Engl. J. Med. 291, 824-828 (1974)

9. Rucker, T. D.: Drug use. Data, sources and limitations. J. Amer. med. Ass. 230, 888-890 (1974)

10. Boethius G., Westerholm, B.: Is the use of hypnotics, sedatives and minor tranquillizers really a major health problem? Acta med. scand. 199, 507-512 (1976)

11. Boethius, G.: The treatment of hypertension - an analysis of drug prescription data. Acta med. scand. 200, Suppl. 602, 120-123 (1976)

12. Vinge, P. G.: Swedish data act. Federation of Swedish Indus- tries 43, p. 8 (Stockholm 1973)

Received: October 27, 1976, accepted: November 3, 1976

Dr. G. Boethius Department of Internal Medicine Ostersunds Hospital S-831 01 Ostersund Sweden