Daytime use of general practice and use of the Out-of-Hours Primary Care Service for patients with chronic disease: a cohort study

The study was based on information on 21,457 randomly sampled patients contacting the OOH services in the Central Denmark Region, which covers approximately 1.3 million residents [9]. These data were originally collected for the ‘LV-KOS2011’ survey (LV-KOS); a large and comprehensive Danish cross-sectional study on disease patterns in the OOH Primary Care Service during a 12-month period in 2010-2011. The survey was carried out by means of pop-up questionnaires integrated into the existing electronic OOH patient administration system. The OOH-GPs were, for instance, asked whether the RFE in question was a new event or an exacerbation of an already diagnosed chronic disease. The GPs included three independent types of contacts to OOH; telephone consultations, clinical consultations, or home visits. The pop-up frequency was adjusted to the GP workload and the sample size required for valid research results; 1 in every 10 telephone contacts, 1 in every 3 clinical consultations, and every home visit. For each of the three types of contact, registered contacts were highly representative of all contacts to the OOH services in the region during the study period, and the participating GPs were representative of all GPs working in the OOH services during the same period [10].

From the data obtained in the LV-KOS survey, we included patients aged 18 years or older. We excluded patients without a unique Danish civil registration (CPR) number, assigned to all Danish citizens [11]. The cohort was categorised with reference to chronic disease defined as heart disease, lung disease, psychiatric disease, diabetes, and cancer by linking the unique Danish CPR [11] with Danish registry data [12].

Eligible patients with the five chronic diseases were identified by using the International Classification Of Diseases (ICD-10) [13] or by a combination of ICD-10 codes, data on prescribed medication according to the Anatomical Therapeutic Chemical (ATC) Classification System [14, 15], and data on health services provided in general practice [16] (Table 1). The registry data used for the identification was obtained for the period of 1 January 2005 until 30 days before inclusion in the LV-KOS study (index date).

Patients with heart disease were defined as patients with unstable angina (ICD-10 I20.0) and post myocardial infarction (ICD-10 I21), and these patients were identified through the Danish National Patient Registry [17]. Patients with diabetes were identified if registered in the National Diabetes Registry [18]. Psychiatric disease was defined as schizophrenia (ICD-10 F20), and schizophrenia and schizoaffective disorders (ICD-10 codes F25), and bipolar affective disorder (ICD-10 codes F30 and F31), and patients were identified in the Danish Psychiatric Central Registry [19]. Patients with cancer were identified if registered with ICD-10 C00-C97, excluding C44 (non-melanoma skin cancers) in the Danish Cancer Registry [20]. Patients with lung disease were identified according to a validated algorithm [21]; ICD-10 J40-J47 or J96 (in the Danish National Patient Registry), or redemption of at least two prescriptions with ATC codes R03AC, R03AK, R03BA, R03BB, R03CC, and R03DA, R03DC (all including subcodes) within the past 12 months, or oxygen treatment with the ATC code V03AN01 (according to the Danish National Prescription Registry [14]), or at least two spirometries with service codes 7113 or 7121 within the past 12 months (the Danish National Health Service Registry [16]). A subgroup of patients was identified by two or more of the five diseases designated as ‘2 + diagnosed’. Patients with more than one of the five chronic diseases were included in the numerator for each specific disease.

Information on face-to-face contacts during daytime general practice (Table 2) was obtained from the Danish National Health Service Register during the 12-month period prior to the index date.

From the LV-KOS survey, we obtained information as to whether the registered RFE was due to an exacerbation of an already diagnosed chronic disease or due to a new health problem.

Descriptive analyses were performed for each of the five chronic-disease patient groups and for the group consisting of 2 + diagnosed patients. The study population was divided according to the LV-KOS survey information on whether the RFE was due to an exacerbation of previously diagnosed chronic disease or of a new health problem. Due to the sampling method (one in ten telephone contacts, one in three clinical consultations, and every home visit), we made weighted analyses using sample weights defined as the reciprocal to the sampling fraction when reporting on all contacts [22].

For each of the five patient groups, we calculated mean number of daytime contacts during one, three, six, and 12 months prior to the index date, proportions of patients in contact with daytime general practice, and proportions of patients with a scheduled and recommended annual follow-up at their own GP for the chronic condition. Continuous data were presented as means with corresponding 95% confidence intervals (95% CI), and proportions were presented in numbers with corresponding weighted percentages. Data on contacts to daytime general practice was analysed as categorical variables in weighted multiple logistic regressions presented as odds ratios (ORs) with the corresponding 95% CI. The ORs for RFEs due to exacerbation were calculated for use of daytime general practice 30 days prior to the index date and for annual follow-up, and were adjusted for age, gender, and type of LV-KOS contact. Adjustments for clustering by practice were made using robust variance estimates. Data were analysed using STATA /MP 12.1 (StataCorp LP, College Station, TX, USA).

The project was approved by the Danish Data Protection Agency (J.no. 2011-41-6365). According to Danish law, approval from the ethical committee was not needed as the study did not include biomedical intervention.

Approximately one third of the study population who had at least one face-to-face contact with the daytime GP during the preceding 30 days had contacted the OOH services due to an exacerbation of a chronic disease; a little less for patients with diabetes or cancer. Use of daytime GP was highly associated with OOH contacts due to exacerbation of chronic disease. Except for patients with diabetes, this association were less likely initiated by patients with at least two of the five chronic diseases who had received an annual daytime follow-up consultation during the 12-month period prior to the OOH contact.

A major strength of this study was the data obtained from the LV-KOS survey. Both the participating GPs and the registered contacts to OOH were highly representative of the organisation and for the contacts provided at the OOH services in the region during the study period [10]. For each OOH contact, the GP noted whether it was due to an exacerbation of an existing chronic disease or due to a new health problem. No previous studies or other data sources provide such specific data on contacts to the OOH services. Furthermore, the identification of patients with the five chronic diseases in question was achieved with high precision and validity by using the unique Danish CPR number as link between the LV-KOS population and the Danish national registries [23‐25].

The LV-KOS contacts revealed no exhaustive information as to whether the registered RFE was related to the chronic diseases identified for the patient in our study or due to a competing chronic disease which was unknown to us. This could lead to misclassification for some patients and thus overestimation of the number of exacerbations for the specific disease. We chose to analyse the five frequently occurring chronic diseases separately although this implied potential implications of comorbidity. To explore the impact of multiple diseases on the outcome, we performed several analyses on the group of patients with at least two of the selected chronic diseases, and these results were comparable to the results obtained for the five disease groups.

Activities in the OOH and medical assessments of RFEs for patients with chronic diseases are poorly described in the literature. However, in a recent retrospective study, Adam et al suggested poor pain management to be the overall dominating RFE with the OOH services among patients with cancer [26]. In our study we found however that patients with cancer who recently consulted the daytime GP more often contacted the OOH services due to a new health problem than patients with other chronic diseases; this finding may indicate a reasonably good overall cancer pain control.

A Norwegian study of contacts to general practice for patients with psychiatric disease found that patients in contact with the OOH Primary Care Service also regularly consulted the daytime GP [27]. The study also concluded that patients seen in out-of-hours care had a high prevalence of severe psychiatric disease symptoms. These results highly correspond with our findings. Our results showed that the OR for exacerbation at the index contact was twice as high for patients with psychiatric disease who had more than two consultations at the daytime GP than for patients with none or 1-2 contacts. This may indicate that patients with psychiatric disease who frequently attend the daytime GP could be the most ill if the exacerbation is regarded as a proxy for the state of health. This may call for increased attention on this group of patients during daytime.

Our study indicates that patients with the five selected chronic diseases are less likely to have an exacerbation at the index contact than other patients, provided that the chronically diseased patients had received an annual follow-up consultation. These findings are in line with the objectives stated in the general guidelines on follow-up consultations for chronic disease cuix. However, despite the proportion of patients with diabetes who had an annual follow-up, the weighted and adjusted estimates showed only minor impact on the OR for exacerbation incidence rates. Despite the specific recommendations on annual follow-up for diabetes and heart disease [28, 29], patients in these two groups had the highest OR for exacerbation at the index contact.