Comparative studies examining the impact of direct to consumer advertising which fulfilled inclusion criteria
| Study and design | Population/setting | Intervention | Outcomes studied and follow up | Results | Comments |
|---|---|---|---|---|---|
| DTCA, direct to consumer advertising. | |||||
| Basara16 Interrupted time series | US primary care | DTCA initiated after 1993.“Brand name” product specific print or television DTCA.Targeted at “common conditions”(excluding “cosmetic or lifestyle”drugs) | New prescription volume(monthly aggregates) of drugs subject to DTCA. Derived from“physician level” prescribing data | DTCA resulted in increased prescribing volume (R2 = 0.90, p<0.00001).The sustained increase in prescription volume was subject to exponential decline as the marketing campaign progressed | Clustering of physician and demographic characteristics accounted for in design and analysis |
| Four representative geographical areas in the US | Migraine treatment (sumatriptan) chosen as an exemplar | Six months data pre DTCA and 11 months post DTCA analysed | Sales response decreased exponentially following termination of DTCA | ||
| Mintzes et al19–21 Comparative cross sectional study | Primary care | DTCA of any type used in US (1999–2000) | Patients belief that they needed medicine | Patients believed that they needed medication more often in Sacramento than in Vancouver (OR 2.6,95%CI 1.5 to 4.3). Specific belief that this should be a DTCA drug also higher (OR 1.4, 95% CI 1.1 to 1.8). Most common request for branded antihistamines | Clustering and demographics accounted for in design and analysis |
| Patients and clinicians in Sacramento (DTCA group N = 683 patients and 38 clinicians) and Vancouver (control group N = 748 patients and 40 physicians) | Patients’ requests for prescriptions | Patients requested specific DTCA drugs more often in Sacramento than in Vancouver (7.3% v 3.2%, OR 2.2, 95% CI 1.2 to 4.1) | |||
| Clinicians’ prescriptions in response to these requests | Patients were more likely to receive a prescription of a DTCA drug than a non-DTCA drug (OR 8.7, 95% CI 5.4 to 14.2); rate similar in Sacramento and Vancouver. Those who requested a specific DTCA drug were more likely to receive a new prescription (for any drug) than those who did not (OR 16.9, 95% CI 7.5 to 38.2) | ||||
| Clinicians’ satisfaction with prescribing decisions | Clinicians more likely to express dissatisfaction or ambivalence with patient requested drugs (OR for requested DTCA drugs 7.1 in Sacramento (95% CI 2.5 to 19.8), 14.5 in Vancouver (95% CI 2.6 to 81.4) | ||||
| ‘t Jong et al18 Interrupted time series | Netherlands primary care | DTCA mass media campaign on onchomycosis (fungal nail infection) by Novartis, a manufacturer of terbinafine | Prescription volume of terbinafine (product of the company initiating the awareness campaign) | Prescription volume for terbinafine increased during the period of the campaign from 6.50 prescriptions per 1000 person years (95% CI 6.33 to 6.66) to 15.2 (95% CI 13.5 to 16.9) | Scant methodological details making it difficult to comment on method of analysis. However, several data points available before and during the campaign. |
| Research database containing prescription information on 150 practices (470775 patients, 1.5 million patient years) between 1996 and 2002 | Advertising campaign between 2000–2001 | Prescription volume of itraconazole (generic drug also available for treating onchomycosis) | Prescription volume of itraconazole fell from 6.84 prescriptions per 1000 person years (95% CI 6.67 to 7.01) to 6.07 (95% CI 5.86 to 6.28) | ||
| New consultation rate for onchomycosis | New consultation rate for onchomycosis increased from 5.9 per 1000 person years (95% CI 5.6 to 6.2) in 1999 to a peak of 8.2 (95% CI 7.9 to 8.6) in 2000–1 and fell to 4.9 (95% CI 4.6 to 5.1) per 1000 person years in 2002 | ||||
| Zachry et al17 Interrupted time series | US primary care | DTCA mass media campaigns for five classes of prescription only medicines (antihistamines, anti-hypertensives, anti-ulcer drugs, benign prostatic hypertrophy?(BPH) drugs, and cholesterol lowering drugs) | Monthly advertising expenditure for named DTCA drugs | A positive association (p<0.05) between advertising expenditure, diagnosis and prescription volume (by class and by named drug) was found for antihistamines, anti-ulcer drugs, and cholesterol lowering drugs | Clustering and intercorrelation of data points included in analyses. Several data points available before and during the DTCA campaign |
| New diagnoses for the advertised drugs’ FDA approved indications | Regression analysis showed that every $1000 spent advertising cholesterol lowering drugs was associated with approximately 32 people diagnosed with hyperlipidaemia and 41 cholesterol lowering drug prescriptions being written | ||||
| Research database containing details of 195577 clinician encounters from 1992 to 1997 correlated with an advertising database detailing all advertising expenditure for named drugs subject to direct to consumer advertising (including TV, radio, print media) | Advertising campaigns between 1992 and 1997. Campaigns had to last for a minimum of 18 months | Prescription volume for drugs belonging to the same class | |||
| Prescription volume for branded drugs subject to DTCA | |||||
| All outcomes pre-advertising and for 19 months during the advertising campaign | |||||