In this descriptive retrospective analysis of the VINCI database (2008–2021), we found that approximately half of the clinical notes of veterans with AD showed concordance between clinicians’ judgement and cognitive test-based assessments of AD severity. The concordance rate was consistent across the clinically defined mild, moderate, and severe AD cohorts (52–54%). A slight rise in the proportion of concordant notes was observed over the 12-year study period. Of note, the overall concordance rates were similar, regardless of whether subjective assessments were compared to objective ratings from either the MMSE or the MoCA; this is consistent with the reported high correlation between these two instruments .
From 2015 onward, the overall trend among discordant assessments was for clinicians’ judgements of severity to be less severe than the instrument-based ratings. In the mild AD cohort, subjective assessment underestimated severity relative to the objective test in approximately 41% of all notes (90% of discordant notes). These findings suggest that in real-world settings, clinician judgement may take into account extra-cognitive considerations such as psychiatric, neuropsychological, behavioral, or functional factors, and thus deviate from the defined MMSE and MoCA thresholds for severity that were used in our study. Furthermore, while these tests are used for dementia assessment in clinical practice, they both lack specificity for AD and low scores are not diagnostic for dementia or AD . Nonetheless, these tests are widely utilized to assist clinical diagnosis of AD, in conjunction with other diagnostic methods such as brain imaging .
Certain symptoms and comorbidities were associated with markedly higher or lower concordance between subjective and objective assessments of AD severity. “Wander” was associated with the highest concordance (73%), possibly because this symptom is a hallmark of AD. In contrast, “delusion” was associated with the lowest concordance (21%), possibly because this symptom may have been attributed to other conditions—in 70% of notes with delusion, the clinician’s assessment of AD severity was less than that of the objective instrument. Among discordant notes associated with most psychiatric symptoms/diseases, our observation that subjective assessments tended to be less severe than objective assessment suggests that clinicians may be considering the independent impact of comorbidities that have overlapping symptoms with AD, and is worthy of further study. Interpretation of disease severity also depends on a clinician’s appreciation of agnosia, a common symptom of Alzheimer’s dementia and this may contribute to the variation and discordance found in this study. In many cases, the reason a particular symptom or comorbidity impacted concordance was not clear, and interpretation may be limited by small numbers of notes with these comorbid conditions.
There are several potential explanations for clinician bias toward lower subjective assessments. First, there is a perceived lack of effective treatments for AD. Second, patients may tend to minimize their symptoms either for social reasons or as a result of agnosia. Third, patients are often interviewed in the presence of family members, who may prefer to minimize symptoms out of concern for patient dignity. Patients and families often understand that a diagnosis of dementia may lead to loss of independence (i.e., driving) and increased demands on families to provide support for transportation, medication management, and financial supervision. Fourth, clinicians may have less time for subjective assessment, when an MMSE or MoCA test is performed. All of these factors may impact clinicians’ use of language when describing dementia in clinical documentation.
In the era of anti-amyloid therapy for AD, identification of patients in early stages of AD is essential to ensure that therapies with the potential to alter the progression of this debilitating disease are initiated in a timely manner in patients who are most likely to benefit. The decision to initiate certain therapies for chronic neurological conditions may be complex, and ideally depends on a precise assessment of disease severity . Unfortunately, the clinical management of AD currently lacks clear, well-defined assessment and treatment guidelines. This is in stark contrast to the current practice paradigm for multiple sclerosis (MS) in which clinicians have evidence-based consensus guidelines [17, 18] and can rely on direct biomarkers (e.g., demyelinating plaque burden assessed quantitatively by magnetic resonance imaging [MRI]; presence of active demyelination assessed by gadolinium-enhanced MRI) [18, 19] to weigh the relative risks and benefits of the therapy.
Disease burden in AD may be estimated by a combination of clinical assessment and measurement of biomarkers of brain amyloid-beta (Aβ) protein deposition (i.e., low cerebrospinal fluid [CSF] Aβ42 and positive positron emission tomography [PET] amyloid imaging), as well as surrogate biomarkers of neuronal injury (e.g., increased CSF tau, decreased fluorodeoxyglucose (FDG) uptake on PET as a marker of metabolic activity, and atrophy measurement by MRI) [3, 20, 21]. Given that biomarkers for AD are indirect and that their measurement may either be prohibitively expensive for patients or dependent on invasive procedures, AD assessments may often be primarily based on clinical evaluation ; clinicians’ subjective assessments are often based on consideration of cognition, function, as well as behavioral symptoms. In practice, clinical evaluation typically entails subjective assessments made by clinicians using a combination of clinical history, patient interview with short cognitive screening instruments, and exclusionary data to rule out other causes of cognitive impairment . Parallel assessments are made using more detailed and objective cognitive assessment tools, such as the MMSE and the MoCA that are solely based on cognition; however, these approaches do not have specificity and sensitivity for AD diagnosis [8, 9, 16].
We performed a post hoc sensitivity analysis to assess whether using ranges that may overlap with a classification of MCI would influence our overall findings; AD severity ranges were drawn from a study that reported the following MMSE cutoffs: 21–25 for mild, 11–20 for moderate, and 0–10 for severe AD . We found that the proportion of assessments that were S > O in the mild AD cohort exhibited a minor increase from 4.7% to 6.7%; overall concordance and discordance findings remained at similar levels (eTable 4 in the supplementary material). To carry out more comprehensive evaluation in future studies comparing objective assessment of AD to clinician’s subjective assessment, the brief interview to detect dementia (e.g., AD8)  and Reisberg Functional Assessment Staging (FAST)  could be incorporated.
The current study provides insight into assessments of AD severity in one of the largest US managed care settings; however, several limitations must be considered. Since there are no ICD codes specific to AD severity stages, we utilized keywords to identify mild, moderate, and severe AD cohorts. This method allowed us to efficiently examine a large volume of clinical note data, but likely missed clinical context that may have clarified some of the discordant findings. For example, the temporal relationship between a clinical assessment and objective assessment that appeared within the same note was not evaluated. Such context would require a validating chart review. In addition, retrospective analyses are inherently more susceptible to confounding variables than prospective studies . We examined factors that could have impacted concordance, such as concurrent symptoms and comorbidities. Symptoms and comorbidities were identified using diagnostic codes, which can be subject to inaccuracy and/or undercoding . We could not explore possible root causes of discordance between subjective and objective assessments of patients with AD since it was beyond the scope of this descriptive study. Clinician’s subjective assessment and test-derived objective assessment are two reiterative processes that are difficult to separate. Furthermore, MoCA screening might only be appropriate for assessment of earlier stages of AD in the elderly, which may have contributed to some of the observed discordance . Finally, these findings from a population of veterans in the VA healthcare system may not be generalizable to the overall US population and healthcare system. While our findings do not specifically address changes that may be needed in clinical practice, they serve to raise awareness regarding discrepancies between subjective and objective assessments of cognitive impairment—these discrepancies can impact clinical decisions.
The burden of AD among veterans is expected to increase, not only as a result of population aging, but also due to the prevalence of other potential risk factors for dementia such as traumatic brain injury and PTSD in this population [28,29,30]. Additional areas of investigation in the veteran’s population include evaluating the impact of AD diagnosis on healthcare utilization and an exploration of whether certain comorbidities may influence the duration of time from MCI diagnosis to onset of AD.