Data from the 2001 and 2002 National Ambulatory Medical Care Survey (NAMCS) were used to assess patterns of depression diagnosis and treatment provided during physician office visits made by patients aged 65 and older. Multiple years are pooled to increase sample size. The NAMCS is a nationally representative survey of physician office visits in the United States conducted annually by the National Center for Health Statistics.23
Visits to physicians in primary care and all specialties (including psychiatry) are included in the sample except for visits to anesthesiologists, pathologists, and radiologists. Encounters not included in the NAMCS are those made by telephone, those made outside of the physician's office, and those made in hospital and other institutional settings. The NAMCS sample of visits is obtained using a 3-stage sampling design selecting primary sampling units (PSUs), physician practices within PSUs, and patient visits within practices. Physicians were asked to record information on visits made over a randomly selected 1-week period during the year. Depending on the size of the practice, the sample of visits during the 1-week period ranged from a 100% sample to a 20% sample. A full description of the NAMCS sampling procedures is provided elsewhere.24
There were 24,281 visits included in the 2001 sample and 28,738 visits included in the 2002 sample. The analysis is limited to all visits during 2001 and 2002 made by patients age 65 and over (N = 14,372). For each office visit, the survey provided information on physician specialty, medical procedures performed, up to 3 diagnoses, and up to 6 medications prescribed, continued, or renewed during the visit.
The NAMCS includes up to 3 listed diagnoses for each visit. Physician office visits for depression were identified using the 3 listed diagnoses assigned by providers during the visit using the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). Depression visits were all visits with ICD-9 codes of 296.2 (major depressive disorder, single episode), 296.3 (major depressive disorder, recurrent), 300.4 (neurotic depression/dysthymia), 311 (depressive disorder, not elsewhere classified), and 298.0 (depressive type psychosis). Using this definition, there were 366 visits by elderly patients included in the study sample. Treatment rates were only assessed for visits with a diagnosis of depression. Although antidepressant prescribing and patient reported symptoms could also theoretically be used to identify depression visits using NAMCS data, identification using antidepressant medications would bias the sample to include visits where treatment was provided and would include visits where antidepressants were prescribed to treat conditions other than depression, while using patient-reported symptoms would include visits where the physician decided that the symptoms were not at a level that warranted a depression diagnosis.
Antidepressant Drug Visits
Antidepressant drugs that were prescribed, supplied, administered, ordered, or continued were identified by drug name. The drugs included in the class of antidepressants were amitriptyline, amoxapine, bupropion, citalopram, clomipramine, desipramine, doxepin, fluoxetine, fluvoxamine, imipramine, isocarboxazid, maprotiline, mirtazapine, nefazodone, nortriptyline, paroxetine, phenelzine, protriptyline, sertraline, tranylcypromine, trazodone, trimipramine, and venlafaxine. There were 717 visits where an antidepressant was prescribed during visits made by elderly patients in the sample.
Psychotherapy/Mental Health Counseling Visits
Psychotherapy and mental health counseling visits were identified by a checkbox on the survey form, indicating whether psychotherapy or mental health counseling was provided or ordered during the visit. This response did not distinguish between referral for psychotherapy/counseling or whether the patient was referred. Therefore, referrals (for any reason) were identified from a question regarding visit disposition.
Reason for and Type of Visit
Visits were identified by the physician using a checkbox as being either for an acute condition or a chronic condition. Physicians also identified via checkbox whether the visit was an initial visit or a follow-up visit.
Physicians were classified into 4 groups: psychiatrists; internal medicine; general/family practice; or all other specialties. Visits to physicians with specialties in internal medicine or general/family practice together comprise visits defined as primary care visits.
The goal of this analysis was to provide national estimates of the number and proportion of depression visits made by elderly patients to internal medicine, family/general practice, or psychiatry. Additionally, for those visits to primary care providers with a diagnosis of depression (N
= 124), rates of antidepressant prescribing and referral to psychotherapy or mental health counseling for visits to internal medicine physicians and to family/general practice physicians were assessed. The NCHS includes weights in the NAMCS to enable the sample to be nationally representative and to estimate standard errors and 95% confidence intervals (CIs) that account for the complex survey design. Statistically significant differences between groups were determined using linear hypothesis tests. All statistical analyses used the survey procedures of Stata statistical software to account for the sampling design of the NAMCS.25