Table 8. Relationship between exposure to information from drug companies and prescribing frequency (by year of publication and then study design/size).
| Exposure to Information from Drug Company | Study (First Author Name) | Results | Change in Prescribing Frequency Results |
| Effect of PSR visits | Ching [78] | Higher levels of detailing for enalapril/hydrochlorothiazide and lisinopril/hydrochlorothiazide was associated with higher levels of demand (prescriptions) | Detailing elasticity 0.1–0.27 (p<0.05) |
| Kreyenbuhl [31] | Meeting PSRs >4 times in the preceding month was not associated with the “add” rather than “switch” strategy for antipsychotic medication prescribing | OR 1.22 (95% CI 0.68–2.20) | |
| Steinman [8] | PSR visits of ≤5 min versus >5 min were not associated with intention to prescribe | No association detected | |
| PSR visits to doctors in a small group were associated with increase in more frequent intention to prescribea | OR 12.9 (95% CI 1.2–138.8)b | ||
| PSR visits were associated with increased gabapentin prescribing if physician's previous gabapentin prescribing was nila | OR 15.1 (95% CI 3.9–58.2)b reference group - medium prescribers of gabapentin | ||
| PSR visits were associated with increased gabapentin prescribing if physician's previous gabapentin prescribing was lowa | OR 8.6 (95% CI 2.4–31.4)b reference group, medium prescribers of gabapentin | ||
| Venkataraman [40] | PSR visits were associated with increased n prescriptions | Beta coefficient: +0.944 (significant with a 95% CI) | |
| Canli [32] | PSR visits were associated with increased antibiotic prescribinga | p = 0.0001* | |
| Chintagunta [42] | Higher levels of detailing were associated with higher market share for that brand in the three of the countries studied and no significant difference in two others | Detailing related change in market share; US; beta coefficient +0.06; t statistic 3 (p<0.05); Germany; beta coefficient +0.73; t statistic 3.6 (p<0.05); France; beta coefficient +4.17; t statistic 7.87 (p<0.05); Italy; beta coefficient +0.24; t statistic 0.96 (p>0.05); UK; beta coefficient +0.29; t statistic 1.61 (p>0.05) | |
| Narayanan [43] | PSR visits were associated with an increase in market share | 1% increase in expenditure on detailing was associated with increases in market shares for promoted drugs ranging from 0.11% to 0.14% (p<0.05) | |
| Verdoux [63] | PSR visits were associated with general practitioners initiating a newer antipsychotic medication | OR 2.80 (95% CI 2.09–3.76); p = 0.0001 | |
| Mizik [45] | PSR visits were associated with increased prescribing of Drugs A, B. and C | Drug A: 1 PSR visit generates 1.56 new prescriptions (95% CI 0.8–2.23) or 0.64 visits to induce one prescription | |
| Drug B: 1 PSR visit generates 0.32 new prescriptions (95% CI 0.22–0.43) or 3.11 visits to induce one prescription | |||
| Drug C: 1 PSR visit generates 0.153 new prescriptions (95% CI 0.11–0.2) or 6.54 visits to induce one prescription | |||
| Donohue [44] | Expenditure on PSR visits is associated with higher probability that the detailed antidepressant is prescribed | Beta coefficient +0.703 (p<0.001) | |
| Stafford [56] | Decreasing promotional expenditure was associated with a decrease in prescribing for alpha blockersc | Decreased with decreased promotion | |
| Manchanda [46] | PSR visits were associated with more new prescriptions | 1.8 detailing visits results in 5 new prescriptions (average result)b | |
| Manchanda and Chintagunta [47] | PSR visits were not associated with a significant change in mean prescriptions | Beta coefficient +0.83 detailing t statistic 0.675 (p>0.05) | |
| More frequent PSR visits were associated with diminishing increases in prescribing | Quadratic term for PSR visits: −0.49; t statistic −0.49 (p>0.05) | ||
| Berndt [48] | PSR detailing were associated with increased cumulative days of therapy | Beta coefficient +0.7414; t statistic 43.12 (p<0.01) | |
| Rosenthal [79] | PSR visits were associated with increased frequency of prescription | Beta coefficient +0.017; t statistic 4.25 (p<0.05) | |
| Prosser [67] | PSR visits were more likely to be cited as a prescribing influence by high prescribers than by low prescribers | OR 7.32 (95% 1.64–32.61); Fisher exact test; p = 0.002 | |
| Azoulay [49] | PSR detailing is associated with diffusion of product information and performance on the product market with marketing activities having a more pronounced effect than scientific information in the form of clinical trial reportsc | Beta coefficient +0.654; t statistic 10.17 (p<0.05) | |
| Gonul [69] | PSR visits in minutes were a positive predictor of medication prescription | Beta coefficient +0.1085; t statistic 5.32 (p<0.001) | |
| Caamano [68] | PSR visits were not associated with the n prescriptions | Adjusted regression coefficient −0.490.001; p = 0.998 | |
| Schwartz [27] | PSR visits to residents were associated with increased initiation of prescriptions for 12 drugsa | p<0.05 for all* | |
| PSR visits were not associated with increased prescription of one medication however for this medication unlike the others there had been more PSR visits in the control group | No association detected (p>0.05)* | ||
| Rizzo [50] | PSR visits were associated with increased prescription sales | Beta coefficient +0.28; t statistic 4.19 (p<0.01) | |
| PSR visits may result in diminishing returns given the quadratic beta coefficient is statistically significant and negative | Quadratic sales coefficient for PSR visits: −0.490.01 (p>0.05) | ||
| Chren [38] | PSR meetings were associated with a formulary request | Multivariate result: OR = 3.4 (95% CI 1.8–6.6); p<0.001 | |
| Berings [72] | PSR visits were not significantly associated with benzodiazepine prescribinga | Linear regression analysis: beta 0.16 (p = 0.05 to 0.1) | |
| Cleary [26] | PSR visits were associated with an increase in prescribing of promoted medications; prescribing of them decreased when they were not promoted | Ceftriaxone 24.2% and 27.8% increase in promoted periods; p<0.05 | |
| Cefotaxime 14.6% and 26.2% increase in promoted periods; p<0.05 | |||
| Ceftazidime (promoted in period I but not promoted in period II): 27.7% decrease when not promoted in period II (p<0.05) and 10% increase in period III after being promoted again; p<0.05 | |||
| Lurie [73] | PSR visits for faculty staff for less than 5 min were associated with more prescribing | Logistic regression coefficient 0.016; p = 0.03 | |
| PSR visits for faculty staff for more than 5 min were not associated with a change in prescribing | p>0.10 (coefficient not presented where result not significant) | ||
| PSR visits for faculty staff for less than 5 min were not associated with an addition to the hospital formulary | Logistic regression coefficient 0.014; p = 0.06 | ||
| PSR visits for faculty staff for more than 5 min were not associated with an addition to the hospital formulary | p>0.10 (coefficient not presented where result not significant) | ||
| PSR visits for residents for less than 5 min were associated with more prescribing | Logistic regression coefficient 0.049; p = 0.003 | ||
| PSR visits for residents for more than 5 min were not associated with a change in prescribing | p>0.10 (coefficient not presented where result not significant) | ||
| PSR visits for residents for less than 5 min were not associated with an addition to the hospital formulary | p>0.10 (coefficient not presented where result not significant) | ||
| PSR visits for residents for more than 5 min were not associated with an addition to the hospital formulary | p>0.10 (coefficient not presented where result not significant) | ||
| Peay [33] | PSR visits were associated with temazepam prescription | Multivariate regression: −0.35 (p<0.002) | |
| Blondeel [81] | Based on responses to 8 case-histories: | Multivariate regression: | |
| First contact with a drug from the pharmaceutical industry was not associated with proneness to prescribe | p = 0.05–0.1 | ||
| Number of PSRs received was not associated with proneness to prescribe | p>0.1 | ||
| Based on prescriptions for actual patients: | |||
| First contact with a drug from the pharmaceutical industry was not associated with proneness to prescribe | p>0.1 | ||
| Number of PSRs received was associated with proneness to prescribe | p<0.05 | ||
| Mackowiak [52] | PSR visit expenditure was not associated with a change market size nor market share for benzodiazepines or diuretics | No association detected | |
| Becker [77] | PSR visits per month were not associated with chloramphenicol prescribing | Gamma statistic 0.236; not significant | |
| Journal advertisements | Hemminki [25] | Journal advertisements were associated with a trend for increased hormone replacement therapy (HRT) prescribing in Estonia | Increased prescriptions |
| Charbit [34] | Journal advertising was associated with increased prescriptions of ARA. When journal advertisements for ACE inhibitors and CCB decreased, their market share also decreased | 10.5% decrease in mean annual advertising of ACE inhibitors associated with 19.3% decrease in market share 11% decrease in mean annual advertising for CCBs associated with 19.3% decrease in market share. 20.5% increase in mean annual advertising rate for ARAs associated with 22.9% increase in market share | |
| Prosser [67] | Journal advertisements were no more likely to be cited as a prescribing influence by high prescribers than by low prescribers | 9% high prescribers versus 0% of low prescribers; Fisher exact test; p = 0.18 | |
| Azoulay [49] | Journal advertisements were associated with diffusion of product information and performance on the product market with marketing activities having a more pronounced effect than scientific information in the form of clinical trial reportsc | Beta coefficient +0.112; t statistic 4.753 (p<0.05) | |
| Jones [70] | Journal advertisements were not associated with PCP prescribing | No association detected | |
| Healthcare Communications [80] | Journal advertisement recognition was associated with increased market share for the advertised medication | 14.5% difference in market share between those physicians not recognising advertisements (19.6%) and those associating the advertisement message with the product (34.1%) | |
| Walton [75] | Journal advertisement recognition was associated with medication prescription | OR 1.68 (95% CI 1.21–2.35)b | |
| Becker [77] | Infrequent use of journal advertisement use was not associated with chloramphenicol prescribing | Gamma statistic −0.186 not statistically significant | |
| Infrequent use of journal advertisements to learn about the usefulness of new medications was associated with reduced chloramphicol prescribinga | Gamma statistic +0.51; p<0.05 | ||
| Attendance at pharmaceutical company-sponsored meeting | Kreyenbuhl [31] | Attendance at pharmaceutical sponsored CME meetings more than once in the preceding month was associated with the “add” rather than “switch” strategy for antipsychotic medication prescribinga | OR 2.32 (95% CI 1.29–4.18); p = 0.005* |
| Venkataraman [40] | Attendance at pharmaceutical sponsored meetings was not significantly associated with prescriptions for 7 out of 12 brands | Beta coefficient −0.659 (significant with a 90% CI) | |
| Narayanan [43] | Attendance at pharmaceutical company-sponsored meetings was associated with an increase in promoted medication market share | A 1% increase in expenditure on “other marketing activities” (including meetings) was associated with increases in market shares for promoted drugs ranging from 0.02% to 0.04% (p<0.05) | |
| Huang [65] | Attendance at pharmaceutical sponsored conferences was associated with more prescriptions of the corresponding sponsored antidepressanta | Pearson correlation coefficient; 2001–2002: 0.87; p<0.01, 2002–2003: 0.73; p<0.01 | |
| Spingarn [39] | Attendance at a pharmaceutical sponsored meeting was not associated with the intention to prescribe the promoted medication where it was indicated | OR 2.51 (95% CI 0.91–6.95) | |
| Orlowski [28] | Attendance at pharmaceutical sponsored meeting was associated with more prescriptions of medications being discussed | Drug A: 81 (±44) prescriptions before, 272 (±117) prescriptions after; p<0.001 (Wilcoxon rank sum) | |
| Drug B: 34 (±30) prescriptions before, 87 (±24) prescriptions after; p<0.001 (Wilcoxon rank sum) | |||
| Bowman [60] | Attendance at pharmaceutical sponsored courses was associated with more prescriptions of medication made by sponsoring company | Before and 6 mo after 3 sponsored course involving sponsoring company's drugs: | |
| Course I: Nifedipine, increase in prescriptions 5.6%; p<0.05* | |||
| Course II: Metoprolol, increase in prescriptions 12.4%; p<0.05* | |||
| Course III: Diltiazem, increase in prescriptions 18.7%; p<0.05* | |||
| Peay [33] | Attendance at pharmaceutical sponsored meeting was not associated with prescription of temazepam | No association detected | |
| Mailed information from pharmaceutical companies | Prosser [67] | Mailed information was no more likely to be cited as an influence by high prescribers than low prescribersa | 9% for high prescribers, 0% for low prescribers; Fisher exact test; p = 0.18 |
| Peay [33] | Mailed information was not associated with a change in temazepam prescribing frequency | No association detected | |
| Dajda [76] | Mailed advertisements to general practitioners was associated with an increase in prescriptions | Correlation coefficient 0.08 | |
| Advertising on clinical software | Henderson [29] | Advertisements on clinical software were not associated with a difference in prescribing for all advertised medications combined | Adjusted OR 0.96 (95% CI 0.87–1.06); p = 0.42 |
| Total promotional investment/summated scores of commercial information use/general use of commercial sources | Greving [30] | Commercial information sources of information were associated with an increase in rates of prescribing of angiotensin receptor blocking medications | OR 2.0 (95% CI 1.5–2.6) |
| Commercial information sources of information were not associated with an increase in the n doctors prescribing angiotensin receptor blocking medications | OR 12.8 (95% CI 0.20–816.58) | ||
| Windmeijer [41] | Expenditure on pharmaceutical promotion was associated with more prescribing | Beta coefficient +0.0137; t statistic 2.98 (p<0.01) | |
| Auvray [57] | Total promotional investment was associated with an increase in the n prescriptions | No statistical measures presented | |
| Peay [33] | Commercial information sources were associated with a preference for temazepam prescribinga | p<0.036 (t test) | |
| Commercial information sources were associated with earlier temazepam prescribinga | p<0.045 (t test) | ||
| Hurwitz [51] | Promotion of the branded leading drug was associated with increased market share especially for acute or sporadic conditions | Beta coefficient +0.295; t statistic 4.34 (p<0.01) | |
| Promotion of “following generic drugs” was associated with reduced the market share for the leading drug | Beta coefficient −0.150; t statistic 2.14 (p<0.05) | ||
| Mackowiak [52] | Expenditure on PSRs and journal advertisements was not associated with a change in market size nor market share for benzodiazepines or diuretics | No association detected | |
| Leffler [53] | The promotional intensity for new products was not associated with increased market share for the entrant product 2 y post introduction | Beta coefficient +0.88; t statistic 1.89, p>0.05 | |
| The promotional intensity for new products introduced over a 9-y period was associated with increased market share for the entrant products | Beta coefficient +1.25; t statistic 2.35, p<0.05 | ||
| Telser [54] | Overall promotional intensity was associated with the market share of entrant drugs in the hospital and drug store market in the period 1964–1968 | Drug store: beta coefficient +1.28; t statistic +2.20 (p<0.05) | |
| Hospital: beta coefficient +1.45; t statistic +2.61 (p<0.05) | |||
| Overall promotional intensity was not associated with the market share of entrant drugs in the hospital and drug market in the period 1968–1972 | Drug store: beta coefficient +1.19; t statistic +0.60 (p>0.05) | ||
| Hospital: beta coefficient +0.608; t statistic +1.20 (p>0.05) | |||
| Information delivered without conventional promotion | Andersen [37] | Participation in pharmaceutical funded research was associated with increase in the sponsoring company's share of asthma drug in practices conducting the trial compared to control practices | 6.7% increase (95% CI 3.0%–11.7%)b |
| Freemantle [35] | PSR visits were not associated with an increase in the prescription of the detailed medication | OR = 1.04 (95% CI 0.83–1.31); p = 0.73 | |
| Dolovich [36] | PSR visits were not associated with a change in the market share of amoxicillin | Intervention group: +0.63% market share, control group: −0.72% market share; p = 0.15 | |
| Kazmierczak [59] | Mailed warning letters regarding tramadol for those with a seizure risk were not associated with a change in prescription rates for tramadola | Before mailing: 10% prescribing rate, after mailing 9% prescribing rate. | |
| Soumerai [58] | PSR visits: Propoxyphene use continued a preexisting decline of about 8% a year during the time when warnings from the manufacturing pharmaceutical company were expressed by PSRs after which time this decline halted, however a statistical association was not shown. Refill rates and rates of overdose did not change following the warningsa | No association detected | |
| Mailed information: Propoxyphene use continued a preexisting decline of about 8% a year during the time when warnings from the manufacturing pharmaceutical company were expressed by PSRs after which time this decline halted, however a statistical association was not shown. Refill rates and rates of overdose did not change following the | No association detected |
a
Study authors reported that exposure to information from drug companies was associated with decreased quality of prescribing.
b
Reported by study authors as statistically significant.
c
Study authors reported that exposure to information from drug companies was associated with increased quality of prescribing.
*Chi-squared statistic.
ACE, angiotensin converting enzyme; ARA, angiotensin receptor antagonist; CCB, calcium channel blocker; CME, continuing medical education.