Sociodemographic characteristics
The primary analysis considered a total of 3 129 289 cases in PCNs (n = 18 207) and RGs (n = 3 111 082) diagnosed with one of the acute non-complicated infections (tonsillitis, sinusitis, otitis media, bronchitis, and URTI). In PCNs, 92.7% of the participating practices were General Practitioners, 4.9% Otolaryngologists, and 2.1% were Pediatricians. In RGs, 73.3% were General Practitioners, 10.6% Otolaryngologists and 14.5% were Pediatricians. The total number of observed cases mentioned above (n = 3 129 289) reflects 2 102 783 patients with a mean of 1.5 cases per patient. In PCNs, 62.8% of the included cases were seen in rural area practices compared to 32.6% of cases in the RGs. Sociodemographic characteristics of patients in PCNs and RGs are presented in Table 2. Mean age of patients was higher in PCNs. In both groups, sex was equally distributed. Across groups and observed indicators, the major patient nationality was German, followed by Eastern European, Turkish, and Arabic Hemisphere. Further nationalities such as Northern European, Southern European, and US American were represented by 4.0% or less each. Patient nationality was not reported for less than 1% of the cases and all cases without this information are considered in the category “other”. A main group difference in terms of insurance status was apparent in the subgroup of retired insurance members (RGs: 10.3%; PCNs 20.8%). Taking these numbers and the average age into consideration, it can be assumed that patients in PCNs were reasonably older.
Table 1
Sociodemographic characteristics of patients in RGs and PCNs across all cases
(n = 3 129 289)
Characteristics | RGs | PCNs |
Age: Mean (SD) | 34.3 (21.07) | 47.5 (18.94) |
Sex: female n (%) | 1 633 772 (52.5) | 10 594 (58.2) |
Nationality: n (%) | German: 2 353 362 (75.6) Eastern European: 548 307 (17.6) Southern European: 109 871 (3.5) Northern European: 29 508 (0.9) Other: 70 034 (2.3) | German: 15 980 (87.8) Eastern European: 1 630 (9.0) Southern European: 355 (1.9) Northern European: 79 (0.4%) Other: 163 (0.9) |
Insurance status: n (%) | Main member: 1 857 770 (59.7) Family: 876 894 (28.2) Retired: 319 600 (10.3) | Main member: 12 278 (67.4) Family: 2 024 (11.1) Retired: 3 787 (20.8) |
Employment “yes”: n (%) | 1 881 657 (60.5) | 12 143 (66.7) |
Antibiotic prescriptions
The observed antibiotics prescription rate for acute non-complicated respiratory infections was 31.7% in RGs and 32.0% in PCNs. Across all observed infections and cases, GPs were the largest group of treating physicians to prescribe antibiotics. In PCNs, the percentage ranged from 87.3–99.7%, in the RGs the range was lower and between 46.9% and 96.7% (See Additional file 1, Supplementary Table 5 for details on the overall distribution of medical specialty of antibiotics prescribing physicians.). In mixed logistic regression models for the primary outcome in PCNs, the specialist group otolaryngologists (OR = 0.465 CI=[0.302; 0.719], p-value < 0.001) and pediatricians (OR = 0.369 CI=[0.135; 1.011], p-value = 0.007) appeared to prescribe less frequently antibiotics compared to general practitioners. Type of practice location and the size of network (< 10 practices – small, 10–19 practices – medium, >=20 practices – large) seemed to not influence the prescription rate. On patient level, women had a higher probability for the prescription of antibiotics compared to men (OR = 1.293 CI: [1.201; 1.392], p-value < 0.001) as well as patients over 18 years (OR = 0.771 CI:[ 0.636; 0.933], p-value = 0.008). An increased CCI implied higher prescription rates.
Table 2 shows results of the mixed logistic regression model for the prescription rates of antibiotics in the PCNs for acute non-complicated infections of the upper respiratory tract using practice and patient-related characteristics as covariates. Documented are the odds ratios (OR), the corresponding confidence interval (CI) limits, standard errors, and the p-value. Detailed results of the regression analysis regarding prescription rates of recommended 1st choice antibiotics and alternatives across all observed cases in PCNs and respective reference groups are given in Table 3. Listed values represent prescription of one total year (Q3 + Q4/2016 and Q1 + Q2/2017).
Table 2
Results of the logistic mixed effects regression model for prescription rates of antibiotics in PCNs for acute non-complicated infections
| Odds Ratio | Lower CI limit | Upper CI limit | St. error | p-value |
Otolaryngologist vs. General Practitioner | 0.465 | 0.302 | 0.719 | 0.222 | < 0.001 |
Pediatrician vs. General Practitioner | 0.369 | 0.135 | 1.011 | 0.514 | 0.053 |
Other spec. groups vs. General Practitioner | 0.251 | 0.075 | 0.844 | 0.618 | 0.026 |
Urbanized vs. rural location | 0.832 | 0.512 | 1.351 | 0.248 | 0.457 |
Urban vs. rural location | 0.901 | 0.693 | 1.192 | 0.138 | 0.489 |
PCN size medium vs. small | 0.960 | 0.634 | 1.453 | 0.212 | 0.846 |
PCN size large vs. small | 1.009 | 0.671 | 1.517 | 0.208 | 0.967 |
Patient age < 18 vs. 18–65 | 0.771 | 0.636 | 0.933 | 0.098 | 0.008 |
Patient age > 65 vs. 18–65 | 1.077 | 0.967 | 1.200 | 0.055 | 0.179 |
Female patients vs. male patients | 1.293 | 1.201 | 1.392 | 0.038 | < 0.001 |
Charlson Index 1 and 2 vs. 0 | 1.562 | 1.436 | 1.700 | 0.043 | < 0.001 |
Charlson Index 3 and 4 vs. 0 | 1.662 | 1.435 | 1.925 | 0.075 | < 0.001 |
Charlson Index > = 5 vs. 0 | 1.760 | 1.505 | 2.059 | 0.080 | < 0.001 |
Table 3
Prescription rates of recommended antibiotics across all cases
| RG cases 1st choice/alternative choice | PCN cases 1st choice/alternative choice |
Tonsillitis %* | 24.0/ 3.8 | 18.8/ 1.2 |
Sinusitis % | 18.7/ 40.6 | 22.1/ 42.2 |
Otitis media % | 41.0/ 32.4 | 28.6/ 37.5 |
Bronchitis % | 18.5/ 43.8 | 23.1/ 38.6 |
Upper respiratory tract infections % | 22.1/** | 18.5/** |
*diagnoses for streptococcal tonsilitis and other pathogen-caused acute forms of tonsillitis that warrant antibiotic therapy are not included |
**no alternative choices defined |
Regression analysis for the prescription rate of recommended antibiotics did not identify common influencing factors over all considered infections. Pediatricians seemed to prescribe more recommended antibiotics compared to general practitioners for patients suffering from URTI. For bronchitis, older patients (> 65 years) had a lower probability to receive a recommended antibiotic prescription than younger patients ( < = 65 years).
The distribution of cases included in Disease Management Programs (DMP) is shown in Table 4. For the DMPs for Type 2 Diabetes mellitus, asthma, COPD and coronary heart disease, the inclusion rate of cases across all PCNs was > 90%. In the RGs, the highest rate was for the DMP Asthma bronchiale (76.8% of the observed cases). In PCNs, 46% of observed cases were registered in a Type 1 Diabetes mellitus DMP, in RGs only 17.7% of the cases were in a DMP. In PCNs, 10.9% of cases were in a breast cancer DMP, in RGs this percentage was 5.1%.
The different levels of needed nursing care (level 1 to 5) were equally distributed across groups. Additionally, the CCI of patients in PCNs showed higher relative frequencies in high index values and lower relative frequencies in low index values compared to RGs. This indicates a higher burden of morbidity in the patient sample in PCNs. The percentage of included cases who needed extended care in a nursing home was 0.6% in PCNs (n = 116) and 0.4% in RGs (n = 13 513). Table 4 also details health status across all cases. (See Additional file 2 for detailed information on CCI per observed infection and respective patient population.)
Table 4
Treatment characteristics and health status across all cases
Treatment characteristics | RG | PCN |
Disease Management Program (DMP): n (%) | Diabetes Type 2: 2 140 035 (68.8) | Diabetes Type 2: 16 754 (92.0) |
Asthma: 2 388 555 (76.8) | Asthma: 16 913 (92.9) |
COPD: 2 042 731 (65.7) | COPD: 16 805 (92.3) |
Coronary heart disease: 2 107 723 (67.7) | Coronary heart disease: 16 767 (92.1) |
Care Level*: n (%) | 1: 1 530 (0.0) 2: 31 036 (1.0) 3: 19 713 (0.6) 4: 10 966 (0.4) 5: 4 011 (0.1) | 1: 23 (0.1) 2: 272 (1.5) 3: 164 (0.9) 4: 65 (0.4) 5: 19 (0.1) |
Charlson Index: n (%) | 0: 2 178 429 (70.0) 1, 2: 757 952 (24.4) 3, 4: 105 140 (3.4) > 5: 69 561 (2.2) | 0: 10 059 (55.2) 1, 2: 5 482 (30.1) 3, 4: 1 334 (7.3) > 5: 1 332 (7.3) |
*The care level reflects the extent to which patients are able to manage their own needs independently. Based on an expected care dependency of at least 6 months, evaluation takes six main aspects into account: mobility, cognitive and communicative abilities, behavioral and psychological issues, self-care, management of disease-related demands and burden, and arrangements of daily life and social contacts [16]. |
Cases in PCNs were older and with a higher morbidity. In line with this, antibiotic prescription rates in PCNs were slightly higher than in the RGs (32% vs. 31.7%). An exception was the prescriptions for Otitis media, where cases were included from the age of two and above. Prescription rates for quinolones were 8.1% in RGs and 9.9% in PCNs and thus, generally moderate to low.
On practice level, the prescription rate of broad-spectrum antibiotics in DDD% showed higher rates in PCNs (Median [Q1-Q3]: 100% [82.4–100]) compared to RGs (Median [Q1-Q3]: 95.9% [66.1–100]). Beta regression models on practice level indicated that specialist groups had a lower prescription rate of broad-spectrum antibiotics than GPs. (See Additional file 2, Supplementary Table 17).
Indication-specific quinolone prescriptions
In PCNs, 11.3% of the observed cases with bronchitis and antibiotics and 9.5% of the cases with URTI and antibiotics received a prescription for quinolones (in RGs 11.4% and 7.7%). Viewed separately, 4.9% of Otitis Media cases, 3.6% of Tonsillitis cases, and 11.2% of Sinusitis cases received a prescription for quinolones in PCNs. With 5.3%, 2.7%, and 9.5%, the respective proportions of quinolone prescriptions were somewhat different in the RGs. Overall, prescriptions for quinolones amounted to 9.9% in PCNs and 8.1% in RGs. In mixed logistic regression models for the prescription rate of quinolones for patients treated with antibiotics in PCNs, urbanization appeared to decrease the prescription of quinolones. An increased CCI implied higher quinolone prescription rates compared to a CCI of 0 (no comorbidity). Detailed results of the logistics mixed effects model are given in Table 5 which details prescription rates of quinolones for patients suffering from acute non-complicated infections of the upper respiratory tract and are treated with antibiotics. Practices are considered as random effect. Documented are the odds ratios (OR), the corresponding confidence interval (CI) limits, standard errors, and the p-value. (See Additional file 1, Supplementary Table 4 for diagnoses that warrant quinolone prescriptions.)
Table 5
Results of the logistic mixed effects regression model for prescription rates of quinolones for patients treated with antibiotics in PCNs
Covariate | OR | Lower CI limit | Upper CI limit | St. error | p-value |
Other spec. groups vs. General Practitioner | 0.617 | 0.277 | 1.374 | 0.408 | 0.237 |
Urbanization vs. rural location | 0.466 | 0.210 | 1.035 | 0.407 | 0.061 |
Urban vs. rural | 0.558 | 0.371 | 0.840 | 0.209 | 0.005 |
PCN size medium vs. small | 1.975 | 1.028 | 3.793 | 0.333 | 0.041 |
PCN size large vs. small | 1.077 | 0.565 | 2.053 | 0.329 | 0.821 |
Patient age > 65 vs. age < = 65 | 1.294 | 0.997 | 1.679 | 0.133 | 0.053 |
Female patients vs. Male patients | 0.928 | 0.757 | 1.136 | 0.104 | 0.467 |
Patients with Charlson Index 1 and 2 vs.0 | 1.864 | 1.469 | 2.366 | 0.122 | < 0.001 |
Patients with Charlson Index 3 and 4 vs. 0 | 3.114 | 2.196 | 4.418 | 0.178 | < 0.001 |
Patients with Charlson Index > = 5 vs. 0 | 3.264 | 2.245 | 4.746 | 0.191 | < 0.001 |
The descriptive subgroup analyses over all patients (PCNs and RG) are in line with regression models. The rates of recommended substances were comparable between genders. Contrasting the participation in DMPs resulted in a small increase in the rate of antibiotics and quinolones for DMP participants, and smaller rates of recommended (alternative) antibiotics for observed diseases. A clear difference is observed for CCI 0 (without comorbidity) versus higher values. Antibiotics and quinolone prescription rates were more than 10% higher for patients with comorbidities and less recommended substances were used for those patients. Detailed results of the descriptive subgroups analysis corresponding to the primary and secondary outcomes are shown in Additional file 2.