Point-of-care laboratory testing in primary care: utilization, limitations and perspectives of general practitioners in Germany

We conducted a cross-sectional questionnaire-based survey study among outpatient general practitioners in Germany. In addition to published research, results and experiences from our qualitative research approaches (focus group discussions and individual interviews) with GPs and POCT manufacturers were incorporated in the design of this study. In total, 2,052 GPs from three German federal states received the questionnaire via mail and were asked to participate in our study (Thuringia: n = 1,378, Bremen: n = 456, Bavaria [Lower Franconia]: n = 218, study period: April 14^th – June 30^th 2022). Due to incorrect address data, 38 letters were returned. Other than working as a GP, no other inclusion or exclusion criteria were applied. Contact information from GPs were derived from existing contact lists at our institutes. Each potential participant was contacted once. Questionnaires were sent back in a prepaid reply envelope. The study complies with the declaration of Helsinki and ethical approval was obtained from the Institutional Research Ethics Board of the Jena University Hospital (Registration No.: 2022–2594-Bef.). The participants received no financial incentives for participating in the survey but we applied several strategies [11] to increase the response rate, including pre-notification (newsletters, homepages, etc.), use of stamped return envelopes, mentioning university sponsorship and unconditional incentives (summary of the survey results and an overview of reimbursable laboratory tests for GP practices listed in the German doctor’s fee scale). This study is part of the project POCT-ambulant (POCT-ambulatory) within the InfectoGnostics Research Campus Jena.

The written questionnaire included twelve questions on POCT utilization and limitations as well as perspectives and attitudes of GPs towards POCT use in the general practice. In addition, participants were asked to provide individual characteristics, including gender, work experience, type of practice, employment status, population size of practice location and federal state. We used Likert scales, multiple choice and open text formats. Open text answers regarding barriers of POCT use were categorized into categories and subcategories in a joint deductive-inductive approach by two researchers (AM, RM). The questionnaire included a short cover letter with information on the survey. The questionnaire was designed with the expertise of an interdisciplinary research team consisting of four experienced GPs and healthcare researchers (JB, FW, GS, IG), a work and organizational psychologist (AM) and a biochemist with expertise in primary care laboratory testing (RM). Following a participatory research approach, we discussed objectives, item selection, phrasing and feasibility of the questionnaire with GPs and other researchers within a 90 min research meeting in January 2021. During the design of the questionnaire, several GPs tested the pre-final questionnaire and commented on comprehensibility, feasibility and the scope of the included questions. Only anonymous data were collected and participants were informed in a written statement that returning the questionnaire to our institute implied their consent for anonymous participation in the study. The German questionnaire and an English translation are provided in the Additional file.

Raw data from the questionnaire were entered into Microsoft Excel 2016. Statistical analyses were performed using R (version 4.1.2) [12] and RStudio (version 2021.09.2) [13]. Missing or invalid values were excluded from the analysis. The Pearson’s Chi² test was used to test for statistically significant differences in categorical variables between groups. The Fisher's exact test for count data was performed when the Chi² approximation was inadequate, e.g. when sample sizes were small or the data were very unequally distributed among the cells of the table. The Kruskal–Wallis rank sum test was used to compare continuous variables (i.e. number of utilized POCTs per GP) from more than two independent groups of equal or different sample sizes. Pearson's product-moment correlation was used to analyse any potential association between the mean number of utilized POCTs per GP and (i) the work experience as GP and (ii) time to receive test results from external laboratories.

From the 2,014 GPs reached, 292 responded and participated in our study, resulting in a response rate of 14.5%. The characteristics of the participating GPs are summarized in Table 1. The majority of participating GPs (75%) had 8 years or more work experience as a GP (median: 15 years, interquartile range: 8—23 years) and 59% were female. Most surveyed GPs were self-employed (85%) and worked in either single-handed (58%) or group practices (33%). The population size of the practice location was nearly equally distributed between rural communities (< 5,000 pop.), small towns (5,000—20,000 pop.), large towns (20,000—100,000 pop.) and urban centres (> 100,000 pop.).

Our survey shows that six POCTs are used by the majority of surveyed GPs (> 50%), which include urine dipstick tests (99%), glucose (urine [91%] and plasma [69%]), SARS-CoV-2 (80%), urine microalbumin (77%), troponin I/T (74%) and prothrombin time / international normalized ratio (65%) (Fig. 1). POCTs for D-dimer, erythrocyte sedimentation rate (ESR), Group A streptococcus (GAS), C-reactive protein (CRP), influenza virus and glycohemoglobin (HbA1c) are used by much fewer GPs in Germany (11- 42%). Other POCTs, such as natriuretic peptides or procalcitonin (PCT) are utilized only by very few GPs (< 6%). Participating GPs rarely reported the use of other POCTs than those included in our questionnaire: vitamin D (n = 2), SARS-CoV-2 antibodies (n = 1), uric acid (n = 1), thyroid-stimulating hormone (TSH) (n = 1), Heliobacter pylori (n = 1) and Borrelia antibodies (n = 1), all of them available as POCTs for professional use in GP practices. Our analyses do not support that GPs from rural areas more frequently utilize troponin I/T POCTs compared to their colleagues from towns or urban centres (p = 0.056, see Additional file sTable 1 for detailed test statistics).

The median number of POCTs used per GP (either regularly or infrequently) was 7.0 (IQR: 5.0–8.0) and the median for regularly utilized POCTs was 5.0 (IQR: 4.0–7.0). The number of utilized POCTs (either regularly or infrequently) did not differ between GP practice type (i.e. single-handed, group practice and ambulatory healthcare centre; p = 0.307) and population size of GP practice location (i.e. rural community, towns and urban centres; p = 0.099) (see Additional file sTable 2). Similarly, work experience as GP and the time to receive test results from external laboratories were not associated with the number of utilized POCTs (p = 0.866 and p = 0.139, respectively).

Nearly all (93%) of the participating GPs perceived POCTs as very or rather useful diagnostic tools in the GP practice, while 7% rated POCTs as not useful (Fig. 2). The reported usefulness of POCTs in the GP practice was not different between GP practice type and population size of the practice location (p = 0.825 and p = 0.533, respectively, see Additional material sTable 3). Although the majority (> 75%) of the surveyed GP perceived POCTs as useful in other primary care settings (i.e., home visits, medical services in nursing homes, and out-of-hours emergency medical services), about 25% of the GPs rated POCT use as not useful in these settings. When asked for a prediction on the importance of POCTs in the next ten years compared to today, the majority (65%) of the surveyed GPs predicted that the importance of POCTs will increase, while 30% of GPs predicted that the importance of POCTs will not change. Relatively few GPs (5%) think that POCTs will lose relevance in the next ten years.

When asked for major limitations and barriers of POCT use in their GP practice, 231 GPs (79%) answered this question. Answers were provided in an open text format and were categorized into five categories. The most frequently (n = 155) reported limitation of POCT use were economic aspects, including high costs of POCTs and inadequate reimbursement (Table 2). Test-related limitations (n = 91), especially concerns regarding diagnostic accuracy, and difficulties to integrate POCT-testing into practice routines (e.g. time and personnel expenses) were also frequently (n = 81) mentioned by participating German GPs as limitations for POCT use. Clinical aspects, such as low frequency of test occasion in GP practices or low impact on clinical decisions, were mentioned relatively infrequently (n = 18) by GPs.

In order to be feasible for routine use, a maximum test duration (from sampling to test result) of 10 min is accepted by 25% of GPs, while a duration of more than 20 min is only adequate for 25% of GPs (median: 15, IQR: 10–20).

When asked on the importance of relevant POCT characteristics, participating GPs ranked high diagnostic accuracy, high user-friendliness (including being integrable into practice routines) and fast test results as the most important characteristics (Table 3). Quantitative test result output and appropriate shelf life were ranked as the least important POCT properties.

Regarding the reason for performing POCTs, GPs ranked immediate decisions on patient management and the increase of diagnostic certainty as the most important reasons (Table 3). Improved patient satisfaction was ranked as the least important reason for performing POCTs.

Our results on the most frequently utilized POCTs are similar to a survey conducted among GPs in the German federal state of Saxony in early 2020 [7]. With the exception of SARS-CoV-2 rapid tests, all frequently utilized POCTs are available for in-vitro-diagnostic purposes since many years. Given the importance of fast test results during the ongoing COVID-19 pandemic, German GPs quickly implemented SARS-CoV-2 POCTs, including molecular tests that are now widely accepted among GPs, medical staff and patients [14, 15]. Notably, besides SARS-CoV-2 rapid tests, only relatively few German GPs surveyed in our study utilize POCTs for infectious diseases, such as CRP (utilized by less than 20% of GPs), influenza (15%), RSV (< 5%) and procalcitonin (< 5%). In contrast, GPs in other European countries, such as Norway and Sweden, more frequently use POCTs (e.g., CRP, group A streptococcus [> 65%]) for acute infections [16].

Our survey shows that the great majority of German GPs rate POCTs as useful diagnostic tools in different primary care settings. The main reasons for performing POCTs are the possibility to decide immediately on further patient care as well as to increase diagnostic certainty of GPs. The positive attitude of participating German GPs towards POCT use is somewhat contrary to the relatively limited spectrum of POCTs actually used in practice, which is explained by multiple factors, including factors on the level of the individual GP but also contextual factors related to the German healthcare system.

A frequently reported limitation by the surveyed GPs is the perceived low diagnostic test performance of POCTs. Although GPs often express concerns regarding test performance, the diagnostic accuracy of many POCTs have improved over time and many are not inferior to standard laboratory tests [17]. Moreover, GPs frequently reported difficulties in integrating POCT-testing into practice routines, which also includes time expenses. In German GP practices, the patient consultation time is 7 min on average [18], which leaves little time for additional diagnostics measures, including POCTs. Importantly, in many treatment situations, rather than using POCTs, GPs base their clinical decision on their clinical experience, patient symptoms and anamnesis as well as external central laboratory analyses.

In addition to these factors, POCT use in GP practices is influenced by factors related to the German healthcare system, such as reimbursement regulations. In fact, lack of adequate reimbursement and high costs of POCTs are the most reported barriers of POCT use. In Germany, reimbursement of in-vitro laboratory tests in GP practices often does not exceed 1.50€ for patients with statutory health insurance (approx. 88% of the German population). As a result, performing POCTs is often not economical efficient for a GP. Moreover, Germany has a sufficient infrastructure of external central laboratories that often provide results on the same day or early the next day after sample collection, which may reduce the actual need for performing POCTs in GP practices. In our survey, 75% of the GPs reported that results from external laboratory analyses are usually available after less than 18 h when the patient sample was sent to the laboratory before noon.

In addition, a variety of other factors is relevant for the GPs’ decision to implement a POCT in practice, but evaluation studies in primary care do often not address these aspects [19]. For example, our survey shows that high user-friendliness and being integrable into practice routines are major test characteristics that POCTs should possess to be considered for use in GP practices. In addition, the views of patients may also play a significant role in German GPs’ consideration of POCTs, which should be addressed in future studies.

There is evidence that GPs in rural areas more commonly apply certain POCTs compared to their colleagues in urban areas, such as troponin I/T [20]. However, our analyses show that troponin I/T use as well as overall POCT utilization and perceived usefulness were not different between GPs from rural areas and those from urban centers. This might be explained by the fact that the ambulatory healthcare infrastructure (laboratory infrastructure [21], availability of GP practices and hospitals [22], etc.) is relatively homogenous across Germany. Moreover, in our study, POCT utilization and perceived usefulness was independent from the clinical experience and practice type. Similarly, a survey among primary care physicians from UK could not identify any significant relationships between demographic factors (time to receive blood test results, distance of practice from nearest emergency department and practice size) and the numbers of conditions for which respondents considered that POCTs would be helpful [23].

The relatively low participation rate of 14.5% and inclusion of GPs from only three out of sixteen German federal states in combination with the overrepresentation of Thuringian GPs raises the question on the generalizability of our results. However, when compared to official statistics [22, 24], our sample of 292 GPs is reasonably representative for the German GP population. For example, the distribution of different practice types as well as the rate of self-employed GPs is very similar to the total German GP population. Moreover, the population size of practice locations resembles the distribution of urban and rural areas in Germany, although in our study GPs from rural areas are slightly overrepresented. Similarly, female GPs are overrepresented (60%) in our study (national ratio of female GPs: 49%).

From our knowledge, our study is the first survey among German GPs on POCT utilization, limitations and attitudes towards POCT diagnostics. The questionnaire was designed by an interdisciplinary research team consisting of GPs and researchers in the field of POCT application. We cannot exclude a selection bias towards GPs with more positive attitude towards POCTs since participation was voluntary. Another limitation is that many questions asked for overall views on POCT use, although answers often dependent on the specific POCT, clinical situation and contextual factors. We addressed this limitation during the design of the questionnaire by selecting aspects and choosing a wording that allowed an overall rating. In addition, participants were asked in the introductory text to take on a superordinate role and give answers that were as generally valid as possible.