Abstract
Background:
The diagnosis of mild cognitive impairment (MCI) is becoming increasingly important for the medical treatment of dementia.
Objective:
The aim of this study was to investigate whether the coded prevalence of MCI changed in the period from 2007 to 2017 compared to dementia diagnoses.
Methods:
This was a retrospective evaluation of diagnostic data from 432 general practitioner (GP) practices and 53 neuropsychiatrist (NP) practices in Germany based on the Disease Analyzer database (IQVIA). The frequencies with which MCI and dementia were diagnosed in these practices were determined. The frequency with which dementia was diagnosed was included to determine whether the change in the frequency of MCI diagnoses was due to the increase in dementia prevalence.
Results:
It was found that the number of GP practices with patients receiving MCI diagnoses increased from 16% to 46%, while the number of NP practices with patients receiving MCI diagnoses increased from 55% to 75%. Moreover, the study found an increase in the coded prevalence of MCI from 0.4 to 1.9 patients/GP practice and from 6.5 to 11.1 patients/NP practice were observed.
Conclusions:
A growing number of GPs and NPs code MCI with increasing frequency. However, the coding frequency of MCI in 2017 corresponded to less than 10% of its true prevalence. A sharp increase in MCI diagnoses can be expected, along with the establishment of preventive and disease-modifying dementia strategies.
INTRODUCTION
The diagnosis of mild cognitive impairment (MCI) is becoming increasingly important for the medical treatment of dementia. A recent report comparing six European countries estimates that the prevalence of MCI in Germany will be 3.7 million patients in 2019 [1]. Based on the true prevalence rates from three older German studies, the following MCI prevalence figures were expected in the past decade: Nixdorf study [2]: over 2.8 million MCI cases; EADC study [3]: between 1.1 and 1.5 million MCI cases in association with Alzheimer’s disease; LEILA 75+ study [4]: over 3.2 million MCI patients.
The diagnosis of MCI will become particularly important in the future if new disease-modifying treatment strategies for dementia that address its biological causes are successfully tested and approved [5, 6]. In addition, new primary preventive strategies are relevant for the diagnosis of MCI. There is increasing evidence that preventive measures during the preclinical stage could significantly reduce the prevalence of dementia [7, 8].
Worldwide, dementia prevalence is expected to increase from 47 million patients with dementia (PWD) in 2015 to almost 131 million in 2050. In Germany, more than 1.7 million patients suffered from dementia in 2016 [9]. By 2050, this number is expected to increase to more than 2.7 million [10]. Reducing the prevalence of dementia through preventive measures and pharmaceutical interventions at the MCI stage would be a major step forward.
These prodromal disease stages of dementia have already found their way into routine care, usually diagnosed as ICD-10 code F 06.7, “Mild cognitive impairment” [11, 12]. However, to date, it is not known to what extent MCI diagnoses have been coded in individual general (GP) and neuropsychiatrist (NP) practices. Examining how the prevalence of patients diagnosed with MCI has developed over the past decade (2017-2017) in the individual GP and NP practices is, therefore, of particular interest with regard to the introduction of preventive and disease-modifying dementia therapies.
METHODS
Data source
The present retrospective study used data from the nationwide Disease Analyzer database (IQVIA). The data contained in this database originate from a nationwide sample of general and specialized practices with a coverage of about 3% of practices [13]. The quality of the information is regularly reviewed by IQVIA, and the representativeness of the Disease Analyzer database for German primary care practices has already been confirmed by previous studies [13].
Study population
For the present study, those 432 GP practices and 53 NP practices that provided continuous data from 2007 to 2017 were selected. The frequencies with which MCI and dementia were diagnosed in these practices were determined. The frequency with which dementia was diagnosed was included in order to determine whether the change in the frequency of MCI diagnoses was due to the increase in dementia prevalence. In addition, the shares of MCI and dementia patients treated with antidementia drugs were determined.
RESULTS
The number of GP practices with at least one MCI diagnosis increased from 16% in 2007 to 46% in 2017. During the same period, NP practices showed an increase in such diagnoses from 55% to 75% (Fig. 1).
Share of practices in which dementia and MCI diagnoses were documented in 2007 and 2017.
The number of patients treated in the selected sample of practices between 2007 and 2017 increased by 14% in GP practices and by 7% in NP practices. At the individual practice level, the number of MCI patients increased from 0.4 to 1.9 patients per GP practice and from 6.5 to 11.1 patients per NP practice. The number of dementia patients per GP practice was 21.9 in 2007 and 29.2 in 2017, while in NP practices it was 86.3 in 2007 and 115.1 in 2017 (Fig. 2). The ratio of MCI to dementia prevalence in GP practices was 1:58 in 2007 and 1:15 in 2017, while in NP practices it was 1:13 in 2007 and 1:10 in 2017 (Table 1).
Number of patients with dementia and MCI diagnoses per practice in 2007 and 2017.
Prevalence of dementia and MCI diagnoses in GP and NP practices in 2007 and 2017
In GP practices, the average age of MCI patients increased from 2007 to 2017, but remained constant in NP practices. By comparison, in both GP and NP practices, the average age of patients with dementia was considerably higher than that of patients with MCI (Fig. 3). Figure 4 shows the percentages of women in patients with dementia and MCI.
Mean age of MCI and dementia patients in 2007 and 2017.
Sex structure of MCI and dementia patients in 2007 and 2017.
A total of 16.2% and 15.0% of patients with dementia received antidementia drug prescriptions in GP practices in 2007 and 2017, respectively. In NP practices, 37.3% and 46.2% of patients received antidementia drug prescriptions in 2007 and 2017 respectively. In 2007 and 2017, 4.3% and 5.5% of patients with MCI received off-label antidementia regimens in GP practices, compared with 12.5% and 9.5% in NP practices (Fig. 5).
Proportion of dementia and MCI patients with at least one prescription of an antidementia drug in 2007 and 2017.
DISCUSSION
The present study shows the strong increase of the MCI diagnosis documentation from 2007 to 2017 in Germany.
Little is currently known about what has motivated GPs and NPs to include MCI diagnoses in their diagnostic repertoire. Various influencing factors can be cited. On the one hand, the GP guideline emphasizes that the examination for cognitive disorders should primarily depend on the patient’s initiative and consent [14]. As in other European countries, only half of all incident dementia cases were diagnosed in primary care practices [15]. This is all the more true for patients with MCI, as only a limited number of cases were diagnosed in GP practices. However, a recent change in attitude towards early dementia diagnoses has been observed in GPs [16]. In addition, it has been shown that financial incentives both for the patient, in the form of contributions by the nursing care fund, and for physicians, in the form of special remuneration for providing psychological examinations, after 2012 have led to an increase in the prevalence of dementia diagnoses made in GP practices [17]. Finally, it should be noted that, in addition to the influence of the media and of the governmental prioritization of the issue (e.g., http://www.allianz-fuer-demenz.de), print magazines accessible to all German physicians provided information that pointed out the significance of MCI (e.g., [7, 18]). These are probably some of the factors that have resulted in more patients visiting GP practices in order to be examined for dementia or to rule out dementia. Those who did not suffer from dementia syndrome but from cognitive impairment were then further cared for according to the German guidelines [19] and presumably underwent serial testing as recommended in the American MCI guideline [20], so as to document the transition to dementia [11].
Even in 2007, the number of patients with MCI was higher in NP practices compared to GP practices. The lower growth rate in 2017 is probably due to the fact that the specialist guideline from 2010 and the revised version from 2016 already paid special attention to the diagnosis of MCI in the context of Alzheimer’s disease [19]. It can also be shown that a change in the spectrum of dementia patients to include the prodromal and early stages of dementia was already evident in the opinion-forming memory consultations conducted at universities before 2007 [21]. Similar developments have also been described in other European countries (e.g., [22, 23]).
In view of the small number of MCI patients compared to the much larger number of patients with dementia— 1:15 in GP practices and 1:10 in NP practices— it can be assumed that the concept of MCI as a prodromal stage of dementia is not of quantitative relevance in the daily routine of GP and NP practices.
The low prevalence of MCI in GP and NP practices in Germany contrasts with available epidemiological studies, which all describe almost twice the prevalence of MCI compared to dementia [1–4]. Against this background, the number of coded MCI diagnoses do not at all correspond to the true prevalence of the disease. It can be assumed that the number of undiagnosed MCI patients treated at physicians’ practices for other disorders is comparable to that of dementia patients. It is therefore possible that the MCI diagnoses documented in practices in 2017 are more of a qualitative indicator of the focus of individual medical practices on prodromal dementia stages. The absolute number of cases in the practices suggests a lack of adequate organizational routines when it comes to the diagnosis of MCI and its therapeutic care [24].
Finally, the distribution of age, sex, and antidementia drug prescriptions suggests that the status of MCI diagnoses in GP and NP practices has a certain degree of validity: MCI patients are significantly younger than dementia patients. The increase in the average age of MCI patients in GP practices is presumably due to changes in reimbursement conditions: geriatric assessments of patients over 70 are funded separately in Germany [17]. The causes of the gender differences found in this study have not yet been determined. A recent review [25] did not describe any significant gender differences regarding MCI. It is also unclear why antidementia drugs were prescribed to MCI patients. Both the German guideline [19] and the most recent U.S. guideline [20] explicitly refer to off-label use and do not recommend the prescription of such drugs. There is a need for further research to determine whether and to what extent the sample of coded MCI patients differs from the totality of undiagnosed, uncoded MCI patients.
The concept of MCI as listed in the ICD-10 is unspecific in routine care and can cover a broad range of disorders. Not every MCI patient with the ICD-10 diagnosis is necessarily a patient who has MCI due to Alzheimer’s disease, according to the DSM-5. Various other conditions may hide behind this diagnosis. It is conceivable that MCI diagnoses may also be made without a psychological evaluation [26]. This assumption could not be verified in the data set available, as it includes no psychological or biomarker-relevant test results. Finally, we were unable to assess whether the dementia group included patients with MCI who were only diagnosed with dementia to justify the prescription of an antidementia drug.
The strength of this study is the very large number of patients available for analysis. In addition, it was possible to observe a large number of individual identical practices over a period of more than 10 years. Therefore, the study provides evidence of changes in diagnostic habits, as well as information about the MCI prevalence in GP and NP practices.
This retrospective study showed a significant increase in MCI diagnoses in GP and NP practices in Germany between 2007 and 2017. However, the coded prevalence was much lower than the true prevalence. A sharp increase can be expected, along with the establishment of preventive and disease-modifying dementia strategies. Initial warnings that the healthcare system is not prepared for future innovations cannot be ignored [5, 27].
DISCLOSURE STATEMENT
Authors’ disclosures available online (https://www.j-alz.com/manuscript-disclosures/18-1180r1).