Documentation and Evaluation of Cognitive Impairment in Elderly Primary Care Patients

Causes of cognitive impairment in the elderly include dementia, delirium, toxic effects of medications, trauma, and psychiatric illness. Dementia is the most common cause, and it implies a decline in cognitive function severe enough to interfere with social functioning. The estimated prevalence of dementia is 3% to 6% for community-dwelling elderly persons aged 65 years and older [1-4], but the prevalence of dementia increases with advancing age [1, 2, 5, 6] and is more common among elderly patients in primary care settings, hospitals, or nursing homes [7, 8]. The annual cost of caring for a patient with Alzheimer disease is estimated to be $47 000 [9], and total national costs for senile dementia in 1991 were estimated to be more than $67 billion [10]. In addition, patients with dementia have been shown to have greater mortality than elderly patients without dementia [5]. Given the prevalence, costs, and morbidity of cognitive impairment, and the availability of several brief screening instruments [11-13], screening for cognitive impairment among elderly patients seen in primary care has been recommended [14-20]. Early recognition and diagnosis of cognitive impairment are believed to be beneficial for at least three reasons. First, a diagnosis provides some comfort to the patient and family by explaining the changes in the patient's behavior and also allows the practitioner to counsel the patient and family about prognosis. Second, an accurate diagnosis of cognitive impairment and assessment of its functional and social effects may facilitate access to rehabilitative, social, and financial services, as well as help inform decisions about competency and guardianship [21-23]. Third, early recognition may allow an opportunity to alter the course of the cognitive impairment. Physicians may be able to do so if diagnostic evaluations show a reversible or partially reversible cause [24-26] or if the rate of progression of a dementing illness or a comorbid illness can be slowed [27-29]. Indeed, routine diagnostic investigations for reversible causes of dementia have been recommended [19, 20, 24]. However, the prevalence of reversible causes of dementia and the clinical utility of routine diagnostic investigations are still being debated [13, 30-35]. Thus, although early documentation of cognitive impairment offers many other benefits, clinicians might appropriately choose either an extensive or a limited diagnostic evaluation for any given patient. Our study had four objectives. First, we determined the prevalence of cognitive impairment by screening a group of urban, elderly, primary care patients using the Short Portable Mental Status Questionnaire (SPMQ). Second, we describe their primary care physicians' rates of documentation and evaluation of cognitive impairment. Third, we compare use of health services in the year after the patient's screening examination. Fourth, we compare practice patterns and use of health services among patients with documented and those with undocumented cognitive impairment. Methods Patients Our study was done in the General Medicine Practice of the Regenstrief Health Center, a multispecialty ambulatory care clinic associated with an urban county hospital [36]. The General Medicine Practice is a university-affiliated primary care practice staffed by 35 general internists on the faculty and 118 internal medicine residents. Beginning in January 1991, all patients aged 60 years and older were screened for cognitive impairment, depression, and alcoholism during their regularly scheduled visits. We excluded prisoners, patients residing in a nursing home, patients unable to speak English, and patients who had hearing impairment. The screening instruments included the Short Portable Mental Status Questionnaire [37], the Center for Epidemiologic Studies Depression scale (CES-D) [38], and the CAGE alcoholism questionnaire [39]. Professional research assistants administered the screening interview to patients at the time of scheduled office visits. Screening scores on the SPMQ completed for the purposes of our study were not revealed to the primary care physicians. Patients with 3 to 4 errors on the SPMQ were considered to have mild cognitive impairment, and patients with 5 or more errors were considered to have moderate to severe cognitive impairment. We corrected the SPMQ score for years of education by allowing an additional error for patients with 8 or fewer years of education [37], but we did not correct scores for race. When administered to community-dwelling elderly persons, the SPMQ has a specificity of greater than 90% and a sensitivity of 50% to 82% (cutoff, 3 or more errors) [12, 40]. The positive predictive value of the test in a community-dwelling patient sample was 87%, and the validity was tested against structured psychiatric assessments [37]. We used the standard cutoff score of 16 or greater on the CES-D to indicate significant symptoms of depression [38]. Patients with two or more positive responses on the CAGE questionnaire were considered to have evidence of alcoholism [39]. Interview data were merged with information routinely collected and stored in the patients' electronic medical records [41]. These data included all outpatient diagnoses as recorded by the patients' physicians. The ICD-9-CM codes for the individual diagnoses for each patient were collapsed into 1 of 40 unique categories. We report only the 20 most common diagnoses. We also determined whether each patient had ever had any of the following: tests for hemoglobin concentrations, serum chemistries, thyroid function, erythrocyte sedimentation rate, syphilis (VDRL or fluorescent treponemal antibody absorption or Treponema pallidum microhemagglutination assay), serum cobalamin levels, and serum folate levels; radiograph of the chest; neuroimaging (computed tomography or magnetic resonance imaging); lumbar puncture; or electroencephalography. We determined whether patients had had neurologic evaluation in the year before or in the year after the screening date and whether they had been prescribed any of the major classes of central nervous system-active medications (anticholinergics, narcotics, antidepressants, benzodiazepines, or major tranquilizers) in the year after the screening date. We determined whether patients had ever received pneumococcal vaccination and whether they had received influenza vaccination or colon cancer screening (hemoccult test, barium enema, sigmoidoscopy, or colonoscopy) in the year after the screening date. We determined whether female patients had had mammography and Papanicolaou smears in the year after the screening date. We also determined whether patients had been prescribed aspirin, a nonsteroidal anti-inflammatory drug, or estrogen replacement in each of the 2 years before the screening date. For use of health services in the year after the screening date, we determined the following: whether patients had been hospitalized or had visited the emergency department and the mean number of these episodes among patients with at least one of these visits; the mean number of outpatient visits, including those to medical and surgical subspecialty clinics; and total outpatient charges, including charges for office visits, outpatient diagnostic testing, and pharmacy services. Mortality was determined as of December 1992 using hospital discharge condition, death summaries, autopsy reports, and the Indiana State Board of Health's death certificate files. Statistical Analysis For dichotomous variables, we used chi-square tests to compare frequencies among patients with no cognitive impairment, mild cognitive impairment, or moderate to severe cognitive impairment. We used analysis of variance to compare the mean log-transformed values for continuous and count variables among these three groups. We also looked for significant differences between those with documented cognitive impairment and those with undocumented impairment. A patient with documented cognitive impairment had an SPMQ score of 5 or greater and had dementia (or a synonymous term such as the organic brain syndrome or Alzheimer disease) listed in their outpatient medical record. With moderate to severe cognitive impairment as the dependent variable, we next used logistic regression to determine which variables were independently associated with cognitive impairment. Because the data used in these models are cross-sectional, these analyses cannot ascribe causality. The multivariable regression was done to determine whether age, education, and race were independently correlated with cognitive impairment even when we controlled for comorbid conditions. In the first model, we included all comorbid medical illnesses as independent variables. In the second model, we included the significant variables from the first model in addition to the demographic variables, with significant bivariate relations including age, sex, years of education, and low serum albumin level. The calculation of patients' SPMQ scores for these models did not include corrections for race or education. For these analyses, we randomly divided the data set in half for derivation and validation sets. We also did logistic regression analyses to determine if cognitive impairment was independently correlated with hospitalization, emergency department visits, outpatient visits, use of preventive health care services, or mortality after we controlled for age, race, and education. Results From January 1991 to May 1993, we contacted 4413 patients aged 60 years and older during routine visits to the primary care practice; 3954 (90%) of these patients completed the SPMQ. One hundred fifteen patients refused the screening examination, 284 were ineligible, and 60 could not complete the SPMQ. Among all patients screened, the mean age was 68 years (range, 60 to 102 years), 68.8% were women, 63.4% were black, 43.6% had 8 or fewer years of education, 10.5% had evidence of alcoholis