original article
Wien Klin Wochenschr (2010) 122 [Suppl 2]: 79–84 DOI 10.1007/s00508-010-1336-y © Springer-Verlag 2010 Printed in Austria
Wiener klinische Wochenschrift The Middle European Journal of Medicine
Explanatory model of prescribing behavior in prescription of statins in family practice Ksenija Tušek-Bunc1,2, Janko Kersnik1,2, Marija Petek-Šter2, Davorina Petek2, Zalika Klemenc-Ketiš1 1 2
Faculty of Medicine, Department of Family Medicine, University of Maribor, Maribor, Slovenia Faculty of Medicine, Department of Family Medicine, University of Ljubljana, Ljubljana, Slovenia
Summary. Aim: To survey attitudes towards prescribing statins in a family practice setting and to develop an explanatory model of determinants for prescribing statins. Methods: A random sample of 250 GPs were drawn from a Slovenian Family Medicine Society register and were contacted by anonymous postal questionnaire between June and October 2006. Results: We found no major differences in decisions among the GPs with regard to their age, sex or time in general practice. We identified six factors that influence statin prescribing behavior in GPs and explain 63.5% of the variation: efficacy and utility explained 14.9% of the variation, personal involvement in drug promotional activities accounted for a further 14.3%, attitudes towards drug marketing 10.3%, patient expectations 9.5%, drug price 8.1% and peer pressure 6.5%. Conclusions: The determinants that influence statin prescribing behavior among GPs in our study covered an array of explanatory items consistent with proposals in the literature but factors differ to some extent from proposed theoretical models. The explanatory model explained a high proportion of the variation in deciding on a particular statin. Efficacy and safety remain important factors in selection of an appropriate drug but are far from being the most or only important factors. Key words: Hydroxymethylglutaryl-CoA reductase inhibitors, hypercholesterolemia, cardiovascular disease, prevention, family practice.
Introduction The costs associated with prescription of drugs are rising and governments urge cost-containment for healthcare. There are enormous variations in the volume and costs of prescribing between different geographical areas and between individual prescribers, sometimes explainable by the patient case-mix [1]. Rational prescribing of drugs depends more on the doctors’ than on the patients’ characteristics [2]. The goal of prescribing is to maximize the Correspondence: Ksenija Tušek Bunc, Koroška 115b, 2000 Maribor, Slovenia, E-mail:
[email protected] wkw 9–10/2010 © Springer-Verlag
effect, minimize risk and costs, and respect patients’ choices [3]. Prescribing behavior can be seen as a cognitive activity: that is, the pros and cons of the behavior are weighed before a drug choice is made. Qualitative studies based on proposed prescriptions for written simulation of standardized patient cases offer deeper insights into prescribing behavior [1, 4]. The decisions depend on physicians’ attitudes towards prescribing of a particular drug, their subjective norms towards prescribing of a particular drug and their personal experiences with that drug [5]. Physicians’ backgrounds, training, practice characteristics, and sources of information and their correlation with prescribing behavior can define the profile of each prescriber [6]. Once a product has become part of a doctor’s personal formulary, it has a propensity to be prescribed routinely through habit rather than through any active problem-solving approach [7, 8]. Side effects, efficacy and personal experience drive the decision process in drug prescribing [1, 9–11]. Among the key influencing factors are those that are medical-evidence based; clinical trials can lower the barriers for adoption of new drugs [12]. Doctors are often influenced by scientific conferences [13], and journal articles have been reported to be one of the most important factors influencing prescribing habits [14]. There are conflicting results for the impact of guidelines on prescribing behavior. In general, regional and national treatment guidelines are an important factor for GPs, whereas international treatment guidelines have an impact mostly on hospital doctors [15]. Nevertheless, in prescribing statins in Dutch general practice, the European guidelines are followed better than national guidelines [16]. Continuing education is an important factor that contributes to changing doctors’ behavior [17]. Physicians are affected by their interactions with the pharmaceutical industry [6, 18–20]. Drug company representatives (PSRs) are the key influence at all stages of the drug adoption process [14, 21]; in addition to supplying information, successful PSRs build brand loyalty and market share, and encourage trial of new products [22]. The vast majority of pharmaceutical companies spent the greatest portion of their promotional budget on the personal selling activities of PSRs [14]. Drug company reputation plays an important role in prescribing decisions [14, 22], and somePrescription of statins in family practice
79
original article
times also a drug’s country of origin. Possible reasons for preference of domestic products, apart from quality and price, are other advantages: boosting national employment, helping the economy, easier after-sales service and maintenance of national pride. Direct mail advertising has been reported as having the least influence on prescribing habits [14]. Detailing and free samples have positive and statistically significant effects on the number of new prescriptions that physicians issue. However, in contrast to the results of earlier studies and the dominant view in the public policy debate, results have shown that the magnitude of these effects ranges only from modest to very small. The major influences perceived by prescribers are regulations introducing list limitations, PSRs, and practices of hospital doctors [23]. Awareness of cost containment differs very much from country to country and depends on reimbursement systems, prescribing limitations, doctors’ limited budgets, incentive schemes, etc. [20, 24]. Apart from these direct financial measures, doctors’ individual views on prescribing costs play an important role [25]. Doctors’ decisions to prescribe generic drugs depend on the perceived risk, work simplification and cost containment. Economic pressure raises the use of generic drugs and increases restrictive behavior towards patient wishes [20]. Doctors with greater patient-centered orientation are slower to relinquish older drugs; those who use pharmacological reference sources and postgraduate facilities are quicker to relinquish a no longer recommended drug [1]. Patients’ expectations and views and doctors’ concerns that the patient may otherwise re-consult have a powerful effect on doctors’ decisions to prescribe [1, 10, 26]. A positive patient’s report reinforces prescribing, but a negative result such as a major side effect is often enough to stop a drug trial [27]. In the introduction of new drug it appears that, in the early stages, professional networks and contacts are important in influencing doctors to start prescribing the drug; later, friendship networks and peer pressure play a role [1, 14, 23]. There are several theoretical models and explanations regarding prescribing behavior. For example, HaaijerRuskamp and Hemminiki [28] distinguish between conditioning factors that affect prescribing on macro level and individual factors that influence individual physicians. The main conditioning factors are: traditions and education, medical teaching and medical thinking, level and distribution of wealth in the country, and the power and vitality of the pharmaceutical industry. The three major individual factors on a micro level of influence are: demand and expectations of the pressure group and society, influence of the pharmaceutical industry and research results, and control measures and regulations imposed by health authorities. Schumock et al. [29] divided factors into drug-related (effectiveness, safety, personal experience, formulary status, costs, etc.), direct (guidelines, recommendation, limitations, restrictions or feedback on prescribing, etc.) and indirect (detailing, free samples, advertisements, events organized by companies, research support, etc). Raisch [30] similarly divided factors into
80
Prescription of statins in family practice
direct (formularies, prescribing restrictions, etc.), indirect (detailing, advertisements, clinical trial results, etc.), and individual and practice (demographics, case mix, organizational structure, etc.). Previous research has focused mainly on partial aspects of prescribing drugs in general. We were unable to identify any study on building an explanatory model of determinants for prescribing behavior, and therefore decided to survey attitudes towards prescribing statins in a family practice setting and develop an explanatory model of determinants for prescribing statins.
Methods Sample and study design A random sample of 250 GPs was drawn from a Slovenian Family Medicine Society register. An anonymous questionnaire survey took place between June and October 2006. A letter of from the president of the Slovene Family Medicine Society inviting participation in the study accompanied the questionnaire. Return envelopes were provided. The return address and free contact phone numbers were booked only for the purpose and the time of the survey.
Questionnaire The questionnaire was based on findings from the literature and suggestions from the research group. The following questions were asked of the participating GPs: age, sex, years in practice, completed vocational training, type of employment status, habits regarding prescription of statins, priorities in deciding on a particular statin and its brand name.
Data analysis Data were analyzed using SPSS 13.0 software (SPSS Inc, Chicago, IL, USA). Ethical approval from the National Ethical Board was obtained.
Table 1. Age groups of the GP respondents Age group
Frequency
Percent
≤40 yrs
38
24.8
41–50 yrs
82
50.9
51–60 yrs
29
18.0
>60 yrs
10
6.2
161
100.0
Total
Table 2. Doctors’ time in family practice Years in practice 30
17
10.5
Total
162
100.0
© Springer-Verlag 9–10/2010 wkw
original article
Table 3. Importance of items influencing doctors’ decisions in choosing a certain statin Item
Important
Not important
Indecisive
No.
%
No.
%
No.
%
Practice guidelines
155
95.7
1
0.6
6
3.7
Efficacy and safety
152
95.6
2
1.2
5
3.1
Clinical status
154
95.1
1
0.6
7
4.3
Personal experiences
150
93.1
3
1.8
8
5.0
Comorbidity
140
86.9
8
5.0
13
8.1
Published clinical trials
111
68.9
11
6.9
39
24.2
Co-payment
81
50.4
38
23.6
42
26.1
Drug price
80
49.4
29
17.9
53
32.7
Domestic product
63
38.9
57
35.1
42
25.9
Peers’ opinion
46
28.6
65
40.4
50
31.1
Patient demands
45
27.9
73
45.4
43
26.7
Time from drug introduction into the market
43
26.7
78
48.4
40
24.8
Relation to PSRs
39
24.1
95
58.6
28
17.3
Company with reputation
36
22.6
89
55.7
35
21.9
Drug promotion
33
20.5
84
52.1
44
27.3
Business relation to drug company
29
18.0
94
58.3
38
23.6
Generic vs. brand drug
28
17.4
95
58.9
38
23.6
Included in the study
24
14.9
110
67.8
28
17.3
Drug samples
2
1.2
151
93.8
8
5.0
Table 4. Factor analysis of attributing items in deciding on a statin Factor 1: efficacy of the drug
Clinical status
0.796
Factor 2: doctors’ personal involvement in drug promotional activities
Factor 3: doctors’ attitudes towards drug marketing
0.048
0.103
Factor 4: perceived patient expectations
Factor 5: drug costs
0.007
–0.071
Factor 6: peer pressure
0.238
Comorbidity
0.779
0.175
–0.259
0.156
–0.151
0.100
Practice guidelines
0.738
–0.128
0.009
0.098
0.034
–0.018
Efficacy and safety
0.685
–0.128
0.228
–0.125
–0.030
–0.013
Business relation to drug co.
0.103
0.820
0.140
0.061
0.257
–0.242
–0.038
0.777
0.229
0.110
0.089
–0.191
Included in the study
–0.222
0.736
0.094
0.005
0.190
0.155
Drug samples
–0.006
0.540
–0.153
0.385
–0.323
0.225
Time from drug introduction into the market
–0.003
0.171
0.675
0.214
0.090
–0.142
0.538
–0.135
0.607
–0.042
0.003
–0.189
Relation to PSRs
Published clinical trials Company with reputation
0.052
0.384
0.457
0.272
0.083
0.153
Personal experiences
0.315
0.239
0.507
–0.363
0.030
0.394
Drug promotion
0.032
0.338
0.576
0.218
–0.036
0.269
Patient demands
–0.047
0.098
0.159
0.686
0.107
–0.030
0.246
0.203
0.172
0.603
0.141
0.124
Drug price
–0.096
0.031
0.132
0.139
0.816
0.126
Co-payment
–0.107
0.272
–0.108
–0.047
0.741
–0.042
Generic vs. brand drug
Domestic product
0.036
0.176
0.114
0.387
0.540
0.002
Peers’ opinion
0.211
–0.104
0.016
0.090
0.077
0.805
Extraction method: principal component analysis; rotation method: Quartimax with Kaiser normalization; rotation converged in 11 iterations. Bold values: items contribute to individual factors. wkw 9–10/2010 © Springer-Verlag
Prescription of statins in family practice
81
original article
Results A total of 163 responses were returned (65.2% response rate). Table 1 shows the age groups of the respondents. Overall, 72.7% were female, 65.4% had finished specialist training in family medicine. Table 2 shows the doctors’ time in practice. We found no major differences regarding GPs’ age, sex or time in practice in relation to decision making. Participants reported on the importance of factors that influenced their decisions in choosing a certain statin (Table 3). We used Quartimax with Kaiser normalization in factor analysis; this revealed six factors influencing statin prescribing behavior in GPs and explained 63.5% of the variation. Efficacy and utility explained 14.9% of the variation, personal involvement in drug promotional activities explained a further 14.3%, attitudes towards drug marketing 10.3%, patient expectations 9.5%, drug price 8.1% and peer pressure 6.5% (Table 4).
Discussion Exploratory factor analysis revealed six distinctive factors that explained 63.5% of the variation in prescribing behavior. These factors are “Efficacy and utility of the drug”, “Doctor’s personal involvement in drug promotional activities”, “Doctor’s attitudes towards drug marketing”, “Perceived patient expectations”, “Drug costs” and “Peer pressure”. There was some overlap with the proposed theoretical explanatory models of other authors [28–30], but there were also a few distinctive differences. Of 63.5% of variation explained, only a small proportion (14.9%) in one factor could be ascribed to medical reasons for choosing a particular statin; all the rest was ascribed to behavioral or outside pressures. Among the highest ranked items influencing GPs’ decisions for a particular statin were patients’ clinical status and comorbidities, which are normally assessed by the doctor, and practice guidelines and efficacy and safety, which are usually reported by somebody else and GPs act accordingly. All four items also compose a distinctive factor “Efficacy of the drug” revealed in factor analysis, which explains 14.9% of the variation. We could link efficacy and safety to the findings of previous research on prescribing [1, 3, 9, 11, 12]. However, the results of our study show that even when we expected socially desirable answers in favor of scientific-medical reasons influencing doctors’ decisions, the answers encompassing hard scientific influences explained a far smaller proportion of the variation than did other factors (Table 4). Health policy makers should take into account specific circumstances of drugs on the market and new drugs entering the market with respect to patient needs for those drugs, and should deliver appropriate scientific statements and introduce list limitations where appropriate [13, 23, 29]. The dissemination of scientific information in particular cultural environments should be taken into account when planning or promoting rational prescribing behavior. Scientific conferences, medical journals, and also other meetings and to some extent even PSRs’ detailing can all gain reputation of a scientific source [23]. Clear
82
Prescription of statins in family practice
statements from professional bodies on the trustworthiness of the information source should help practitioners to avoid biased information [15]. The pharmaceutical industry exerts high pressure on doctors, with frequent visits to their offices [20]. Not surprisingly “Relation to PSRs” was ranked higher than other items from this group, acknowledging industry practice in extensive use of PSRs in drug promotion. This has opened a Pandora’s box of “Personal involvement in drug promotional activities”, a factor composed of items lowest on the list of items felt important in influencing GPs’ decisions in choosing a certain statin, explaining 14.3% of the variation. Apart from supplying information, successful PSRs build brand loyalty and market share, and encourage trial of new products [22]. On the other hand, this finding gives opportunity to insurance companies and state agencies to use the same method of changing doctors’ behavior. We found that personal involvement in drug promotional activities and attitudes towards drug marketing play important roles in decisions on drug prescribing [8, 29]. This gives rise to concern, as doctors might be too close to the commercial sources of information [1, 23]. Physicians are known to be affected by their interactions with the pharmaceutical industry [8]. Statistical analysis has shifted “Personal experiences” from a group of items on drug quality into the group of marketing-dependent items. Personal experiences have become an imprecise concept in the era of evidence-based medicine but they are one of the keystones of psychological characteristics of the prescribing doctors who relay the one-to-one reports on positive or negative reports of their patients [27]. “Personal experiences” is a very highly ranked, and among PSRs often used, but nevertheless imprecise item and is one of five in the third factor “Doctor’s attitudes towards drug marketing”. The analysis clearly showed that personal experience does not resemble individual research findings or quality assurance activities at the individual level, but is probably a marketing construct that helps PSRs to involve doctors in the subject matter introduced by them during detailing. However, we cannot avoid the effect of personal experience on prescribing behavior [5, 9] and need to be aware of its subjectivity and bias. Apart from “Published clinical trials”, other items ranked relatively low on the list of items felt important in influencing GPs’ decisions in choosing a certain statin. This factor explained 10.3% of the variation. Patient opinions and desires also drive the decisionmaking processes [1, 26]. “Perceived patient expectations” explained only 9.5% of the variance and, in addition to “Patient demands”, is also composed of items on giving priority to generic vs. brand products, reflecting current societal friction steered by cost-containment policies, preference for generic drugs by health policy makers, and general public opinion of the benefit of brand-name products. Also often disputed, doctors’ awareness of cost-containment has been shown to play an important role in their drug-selection decisions [24, 25, 27]. The “Drug price” factor is composed of three items on co-payment, price of the drug and domestic origin of the drug, that are ranked in the middle of the priority list, explaining 8.1% of the variance.
© Springer-Verlag 9–10/2010 wkw
original article
We also found a distinctive but limited factor of peer pressure, earlier reported as the role of friendship networks [1]. Interestingly, peer pressure ranked in the middle of the list explaining only a modest 6.5% of the variation.
References 1. 2. 3.
Conclusions The study has revealed important new insights into the determinants that influence family doctors in choosing a statin for their patients. With the explanatory model, we were able explain a high proportion of the variation in deciding on a particular statin. We were not able to study the possible impact of the lists and regulations, as those were the same for all doctors involved in the study. The determinants that influence statin prescribing behavior in the GPs in our study covered an array of explanatory items consistent with proposals in the literature, but the composed factors differed in some respects from proposed theoretical models. Efficacy and safety remain important factors in selection of an appropriate drug but are far from being the most or only important factors. Health policy makers should be aware that there are other factors in addition to scientific input that determine drug selection by the doctors and that some can be controlled by governments to promote rational prescribing in relation to drug costs. Peer pressure can build up in an environment where health policy makers acknowledge the high status of primary care, as opposed to the specialist-driven healthcare system. Reporting on doctor–patient communication [31] and on educated patients is more difficult, as the pharmaceutical industry has already influenced public opinion through the media and even more through special patient support groups that pursue the introduction of new costly drugs exclusively for the groups of patients they represent. Having the support of the industry, such groups are far from being an independent public voice. In addition, pharmaceutical companies can use these findings in continuing their marketing strategies by building good attitudes towards marketing of their products through their PSRs and other company name-building activities through involvement of doctors. To keep the relationship between the pharmaceutical industry and medical doctors within ethical norms, guidelines should be developed. The role of PSRs in prescribing patterns should be studied.
Acknowledgments
4. 5.
6.
7. 8. 9. 10. 11.
12. 13. 14. 15. 16.
17. 18. 19.
We acknowledge the contribution of the family doctors who participated in the study. 20.
Financial The study was supported by unconditional grants from the National Research Funding Agency (ARRS) and National Insurance Institute (ZZZS).
21. 22. 23.
Conflict of interest The authors declare no conflict of interest. wkw 9–10/2010 © Springer-Verlag
Bradley CP (1991) Decision making and prescribing patterns – a literature review. Fam Practice 8: 276–87 Haayer F (1982) Rational prescribing and sources of information. Soc Sci Med 16: 2017–23 Barber N (1995) What constitutes good prescribing? BMJ 310: 923–5 Car J, Svab I, Kersnik J, Vegnuti M (2003) Management of lower urinary tract infection in women by Slovene GPs. Fam Pract 20: 452–6 Lambert BL, Salmon WJ, Stubbings J, Gilomen-Study G, Valuck RJ, Kezlarian K (1997) Factors associated with antibiotic prescribing in a managed care setting: an exploratory investigation. Soc Sci Med 45: 1767–79 Gill PS, Dowell A, Dowell H, Conrad M (1997) Effect of doctors’ ethnicity and country of qualification on prescribing patterns in single handed general practices: linkage of information collected by questionnaire and from routine data. BMJ 315: 1590–4 Connolly JP, McGavock H (2000) Repeat prescribing: Which diagnoses, which drugs? Pharmacoepidemiol Drug Saf 9: 305–11 Groves KEM, Flanagan PS, MacKinnon NJ (2002) Why physicians start or stop prescribing a drug: literature review and formulary implications. Formulary 37: 186–94 Denig P, Haaijer-Ruskamp FM, Zusling HD (1988) How physicians choose drugs. Soc Sci Med 27: 1381–6 Bradley CP (1992) Factors which influence the decision whether or not to prescribe: the dilemma facing general practitioners. BJGP 42: 454–8 Majumdar SR, Inui TS, Gurwitz JH, Gillman MW, McLaughlin TJ, Soumerai SB (2001) Influence of physician specialty on adoption and relinquishment of calcium channel blockers and other treatments for myocardial infarction. J Gen Inter Med 16: 351–9 Denig P, Haaijer-Ruskamp MF, Wesseling FM, Versluis AH (1991) Impact of clinical trials on the adoption of new drugs within a university hospital. Eur J Clin Pharm 41: 325–8 Allery LA, Owen PA, Robling MR (1997) Why general practitioners and consultants change their clinical practice: a critical incident study. BMJ 314: 870–4 Kalb CC (1978) Psychological motivations in physician prescribing habits. Med Mark Media 13: 43–55 Kasje WN, Denig P, De Graeff PA, Haaijer-Ruskamp MF (2004) Physicians’ views on joint treatment guidelines for primary and secondary care. Int J Qual Health Care 16: 229–36 Mantel-Teeuwisse AK, Klungel OH, Hofman A, Verschuren MWM, Trienekens PH, Porsius AJ, et al (2006) Prescribing behaviour according to Dutch and European guidelines on the management of hypercholesterolaemia (1992–1999). Br J Clin Pharm 61: 592–600 Accessed 26 06 08 at http:// wwwpubmedcentralnihgov/articlerenderfcgi?artid=1885064 Cantillon P, Jones R (1999) Does continuing medical education in general practice make a difference? BMJ 318: 1276–9 Cooper RJ, Schriger DL (2005) The availability of references and the sponsorship of original research cited in pharmaceutical advertisements. CMAJ 172: 487–91 Muijrers PEM, Janknegt R, Sijbrandij J, Grol RPTM, Knottnerus JA (2005) Prescribing indicators, development and validation of guideline-based prescribing indicators as an instrument to measure the variation in the prescribing behaviour of general practitioners. Fam Pract 60: 624–30 Kersnik J, Peklar J (2006) Attitudes of Slovene general practitioners towards generic drug prescribing and comparison with international studies. J Clin Pharm Ther 31: 577–83 Peay MY, Peay ER (1988) The role of commercial sources in the adoption of a new drug. Soc Sci Med 26: 1183–9 Creyer EH, Hristodoulakis I (1998) Marketing pharmaceutical products to physicians. Mark Health Serv 18: 35–8 Taylor RJ, Bond CM (1991) Change in the established prescribing habits of general practitioners: an analysis of initial prescriptions in general practice. BJGP 41: 244–8 Prescription of statins in family practice
83
original article
24. Avery AJ, Heron T (1997) Poles apart? The views of general practitioners and family health services authority advisers on prescribing cost issues. BJGP 47: 347–51 25. Avery AJ, Wetzels V, Raymond RS, O’Neill C (2000) Do GPs working in practice with high or low prescribing costs have different views on prescribing cost issues? BJGP 50: 100–4 26. Elwyn G, Edwards A, Britten N (2003) “Doing prescribing”: how doctors can be more effective. BMJ 327: 864–7 27. Armstrong D, Reyburn H, Jones R (1996) A study of general practitioners’ reasons for changing their prescribing behaviour. BMJ 312: 949–52
84
Prescription of statins in family practice
28. Haaijer-Ruskamp FM, Hemminki E (1993) The social aspects of drug use. Drug utilization studies: methods and uses. WHO Reg Publ Eur Ser 45: 97–124 29. Schumock GT, Walton SM, Park HY, Nutescu EA, Blackburn JC, Finley JM, et al (2004) Factors that influence prescribing decisions. Ann Pharmacother 38: 557–62 30. Raisch DW (1990) A model of methods for influencing prescribing: Part II. A review of educational methods, theories of human inference, and delineation of the model. Ann Pharmacother 24: 537–41 31. Kersnik J, Kuralt M (2008) Are frequent attenders also heartsink patients? Acta Medico Biotehnica 1: 44–50
© Springer-Verlag 9–10/2010 wkw
