Background
Methods
Study design
Population
Primary endpoint and collected variables
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Higher efficacy of the brand-name drug compared to the generic drug (prescriber’s assessment)
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Concern that the generic drug is not bioequivalent to the brand-name drug
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Occurrence of benign adverse effects (AEs) observed by the prescriber
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Occurrence of serious AEs (overdose, anaphylactic reaction, blood abnormalities...) observed by the prescriber
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Scientific guidelines advising against substitution (peer-reviewed articles, regulatory agency guidelines …)
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Patient’s request: when the patient objects to substituting the drug
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Existence of a risk when switching related to:
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○ Patient comorbidity
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○ Polypharmacy and risk of drug interactions
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○ Age of the patient over 65.
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Prescriber’s personal choice for other reasons (routine, desire to use drug names the patient is familiar with …).
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Age and sex of prescribers. Age was treated as a continuous variable.
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Rate of INN prescriptions: lower or higher than 15% of total prescriptions (national average in 2013: 13.2%)
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Participation in a quality circle with reviews of clinical cases
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The use of E-Prescribing system software (EPS)
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Setting (city/ rural setting).
Results
Population
Characteristic | n or mean (total n = 277) | % or SD |
---|---|---|
Sex: Female – n, % | 99 | (35.7) |
Age: mean (SD) | 52.2 | (11.1) |
Setting: City (versus rural area) – n, % | 128 | (46.2) |
Type of practice: Alone (versus group practice) – n, % | 92 | (33.2) |
Use of Electronic Prescription Software (EPS): Yes – n, % | 235 | (84.8) |
Use of INNa: ≥ 15% | ||
– n, % | 156 | (56.3) |
Use of the NGSb mention | ||
– n, % | – | – |
< 5% | 119 | (43.0) |
≥ 5% | 158 | (57.0) |
5–15% | 102 | (36.8) |
15–25% | 33 | (11.9) |
> 25% | 23 | (8.3) |
Factors related to prescribers
Variable | NGSa mention < 5% of prescriptions n = 119 | NGSa mention ≥5% of prescriptions n = 158 | p value |
---|---|---|---|
Age of prescriber (mean, SDb) | 53.2 (10.8) | 51.5 (11.3) | 0.44 |
Sex: Female (n, %) | 36 (30.3) | 63 (39.9) | 0.10 |
Use of INNc: < 15% (n, %) | 44 (37.0) | 77 (48.7) | 0.05 |
Participation in a quality circle: Yes (n, %) | 77 (64.7) | 87 (55.1) | 0.11 |
Use of EPSd: Yes (n, %) | 109 (91.6) | 126 (79.8) | 0.006 |
Place of practice: City (versus rural settings) (n, %) | 47 (39.5) | 82 (51.9) | 0.04 |
General reasons for not substituting expressed by prescribers
Reasons for not substituting medication a | NGS b mention < 5%: n (%) | NGS b mention ≥5%: n (%) | p value |
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Patient age over 65 | 17 (14.5) | 69 (44.0) | < 0.001 |
Higher efficacy of the brand-name drug | 19 (16.1) | 44 (28.2) | 0.02 |
Does not believe in bioequivalence | 21 (17.7) | 45 (28.9) | 0.03 |
Benign adverse effect | 21 (17.7) | 37 (23.7) | 0.22 |
Severe adverse effect | 27 (22.7) | 31 (20.0) | 0.59 |
Monographies and scientific journals | 7 (6.2) | 15 (10.1) | 0.26 |
Regulatory agency guidelines | 11 (9.6) | 8 (5.5) | 0.21 |
Advice by specialist | 20 (17.2) | 32 (20.7) | 0.48 |
Patient request | 47 (39.8) | 102 (65.0) | < 0.001 |
Patient comorbidity | 11 (9.3) | 56 (36.4) | < 0.001 |
Polypharmacy | 16 (13.7) | 61 (39.4) | < 0.001 |
Physician’s personal choice for other reasons (routine, desire to use drug names the patient is familiar with …) | 4 (3.4) | 12 (7.9) | 0.12 |
Multivariable analysis
Variable | Adjusted Odds Ratio (aOR) | 95% Confidence Interval (95% CI) | p value |
---|---|---|---|
INNa: < 15% | 1.08 | 0.62–1.90 | 0.78 |
Practice: in cities (versus rural areas) | 1.59 | 0.93–2.74 | 0.09 |
EPSb | 0.46 | 0.20–1.05 | 0.07 |
Higher efficacy of brand-name drug | 1.52 | 0.70–3.30 | 0.29 |
Does not believe in bioequivalence | 0.92 | 0.41–2.05 | 0.84 |
Patient request | 2.52 | 1.46–4.35 | 0.001 |
Patient comorbidity | 2.79 | 0.96–8.04 | 0.06 |
Polypharmacy | 1.00 | 0.37–2.73 | 0.99 |
Age of patient over 65 years | 2.33 | 1.03–5.30 | 0.04 |
Differences between therapeutic classes
Therapeutic class | NGS mention use | ||||
---|---|---|---|---|---|
Never (0%) | Rarely (1–24%) | Sometimes (25–49%) | Often (50–74%) | Very often/always (75–100%) | |
Thyroid hormones – n, % | 21 (7.6) | 30 (10.8) | 30 (10.8) | 62 (22.4) | 134 (48.4) |
Antiepileptic drugs – n, % | 31 (11.2) | 51 (18.4) | 48 (17.3) | 68 (24.6) | 79 (28.5) |
Antiplatelet agents – n, % | 45 (16.2) | 110 (39.7) | 40 (14.4) | 60 (21.7) | 22 (7.9) |
Proton pump inhibitors – n, % | 74 (26.7) | 117 (42.2) | 40 (14.4) | 38 (13.7) | 8 (2.9) |
Neuroleptics – n, % | 95 (34.3) | 107 (38.6) | 44 (15.9) | 25 (9.0) | 6 (2.2) |
Oral antidiabetic drugs– n, % | 85 (30.7) | 115 (41.5) | 48 (17.3) | 23 (8.3) | 6 (2.2) |
Statins – n, % | 88 (31.8) | 124 (44.8) | 38 (13.7) | 22 (7.9) | 5 (1.8) |
Antidepressants – n, % | 74 (26.7) | 117 (42.2) | 57 (20.6) | 25 (9.0) | 4 (1.4) |
Hypnotic drugs – n, % | 80 (28.9) | 125 (45.1) | 40 (14.4) | 29 (10.5) | 3 (1.1) |
Angiotensin converting enzyme inhibitors/Angiotensin II receptor blockers – n, % | 81 (29.2) | 120 (43.3) | 48 (17.3) | 25 (9.0) | 3 (1.1) |
Step II-III analgesics – n, % | 106 (38.3) | 109 (39.4) | 47 (17.0) | 12 (4.3) | 3 (1.1) |
Diuretics – n, % | 106 (38.3) | 123 (44.4) | 31 (11.2) | 15 (5.4) | 2 (0.7) |
Antispasmodic drugs – n, % | 139 (50.2) | 96 (34.7) | 30 (10.8) | 10 (3.6) | 2 (0.7) |
Anti-inflammatory drugs (Nonsteroidal and steroidal) – n, % | 118 (42.6) | 108 (39.0) | 40 (14.4) | 9 (3.2) | 2 (0.7) |
Beta blockers – n, % | 88 (31.8) | 128 (46.2) | 36 (13.0) | 24 (8.7) | 1 (0.4) |
Antibiotics – n, % | 107 (38.6) | 108 (39.0) | 39 (14.1) | 22 (7.9) | 1 (0.4) |
Step I analgesics – n, % | 138 (49.8) | 100 (36.1) | 25 (9.0) | 13 (4.7) | 1 (0.4) |
Oral contraceptives – n, % | 116 (41.9) | 114 (41.2) | 34 (12.3) | 13 (4.7) | 0 (0.0) |
Drug | Most frequent reasons for using the NGSa mention | |||||
---|---|---|---|---|---|---|
Patient request | Benign adverse drug reaction | Severe adverse drug reaction | Biological or clinical inequivalence to the brand-name drug | Class with increased risk (inter-individual variations, interactions, narrow therapeutic range …) | Compliance with specialist prescription | |
Antiplatelet agents - n, % | 64(27.6) | 11 (4.7) | 8 (3.4) | 28 (12.1) | 41 (17.7) | 80 (34.5) |
Thyroid hormones - n, % | 29 (11.3) | 7 (2.7) | 3 (1.2) | 105 (41.0) | 73 (28.5) | 39 (15.2) |
Antiepileptic drugs - n, % | 41 (16.7) | 2 (0.8) | 3 (1.2) | 55 (22.4) | 91 (37.0) | 54 (22.0) |
Antiacids - n, % | 112 (55.2) | 31 (15.3) | 3 (1.5) | 47 (23.2) | 6 (3.0) | 4 (2.0) |
Antispasmodic drugs - n, % | 106 (76.8) | 14 (10.1) | 1 (0.7) | 14 (10.1) | 2 (1.4) | 1 (0.7) |
Step I analgesics - n, % | 107 (77.0) | 14 (10.1) | 1 (0.7) | 9 (6.5) | 6 (4.3) | 2 (1.4) |
Step II/III analgesics - n, % | 104 (60.8) | 30 (17.5) | 3 (1.8) | 24 (14.0) | 7 (4.1) | 3 (1.8) |
Anti-inflammatory drugs - n, % | 89 (56.0) | 34 (21.4) | 8 (5.0) | 17 (10.7) | 10 (6.3) | 1 (0.6) |
Antibiotics - n, % | 86 (50.3) | 45 (26.3) | 6 (3.5) | 24 (14.0) | 8 (4.7) | 1 (0.6) |
Antidepressants - n, % | 110 (54.2) | 28 (13.8) | 2 (1.0) | 33 (16.3) | 17 (8.4) | 13 (6.4) |
Hypnotics/Benzodiazepines - n, % | 143 (72.6) | 15 (7.6) | 1 (0.5) | 23 (11.7) | 10 (5.1) | 5 (2.5) |
Neuroleptics - n, % | 94 (51.6) | 20 (11.0) | 2 (1.1) | 18 (9.9) | 26 (14.3) | 22 (12.1) |
Statins - n, % | 105 (55.6) | 42 (22.2) | 8 (4.2) | 16 (8.5) | 10 (5.3) | 8 (4.2) |
Oral anti-diabetic drugs - n, % | 83 (43.2) | 55 (28.6) | 2 (1.0) | 30 (15.6) | 14 (7.3) | 8 (4.2) |
Diuretics - n, % | 102 (59.6) | 22 (12.9) | 2 (1.2) | 20 (11.7) | 14 (8.2) | 11 (6.4) |
Beta blockers - n, % | 94 (49.7) | 25 (13.2) | 3 (1.6) | 29 (15.3) | 19 (10.1) | 19 (10.1) |
Angiotensin-converting-enzyme inhibitors/ Angiotensin II receptor blockers - n, % | 100 (51.0) | 35 (17.9) | 1 (0.5) | 25 (12.8) | 13 (6.6) | 22 (11.2) |
Oral contraceptives - n, % | 110 (68.3) | 19 (11.8) | 2 (1.2) | 16 (9.9) | 12 (7.5) | 2 (1.2) |