@article {1418, title = {Temporal patterns of antihypertensive medication use among older adults, 1989 through 1992. An effect of the major clinical trials on clinical practice?}, journal = {JAMA}, volume = {273}, year = {1995}, month = {1995 May 10}, pages = {1436-8}, abstract = {

OBJECTIVE: To describe the changing patterns of antihypertensive medication use in the years immediately before and after the publication of the results of three major clinical trials of the treatment of hypertension in older adults.

DESIGN: In this cohort study, adults 65 years or older were examined annually on four occasions between June 1989 and May 1992, and the use of antihypertensive medications was assessed by inventory at each visit. The four visits defined the boundaries of three study periods. For each study period, participants receiving antihypertensive therapy were either continuous users (n = 1667, 1643, and 1605, respectively) or starters (n = 157, 142, 120) of hypertensive therapy. The large clinical trials that convincingly proved the efficacy and safety of low-dose diuretic therapy in older adults were published during the latter parts of period 2 and the early parts of period 3.

RESULTS: Among starters, the proportion initiating therapy on diuretics increased from 35.9\% in period 2 to 47.5\% in period 3, significantly so among women (P = .04). The proportions initiating other drugs displayed no significant trends. Among continuous users, the use of diuretics, beta-blockers, and vasodilators generally decreased over the 3-year period, while the use of calcium channel blockers and angiotensin-converting enzyme inhibitors increased significantly in each of the three periods (P < .05). The decline of 2.7\% in the prevalence of diuretic use in period 1 abated during period 2 (1.8\% decline), and it slowed significantly (P = .03) to almost a complete halt during period 3 (0.2\% decline). The rate of increase in the use of calcium channel blockers slowed significantly (P = .01) between period 1 (+6.7\%) and period 3 (+2.8\%).

CONCLUSIONS: Although other factors such as cost may have been important, the temporal trends in antihypertensive drug therapy coincided in time with and may have reflected in part the influence of the major clinical trials on the patterns of clinical practice.

}, keywords = {Aged, Antihypertensive Agents, Clinical Trials as Topic, Data Interpretation, Statistical, Drug Utilization Review, Female, Humans, Hypertension, Male, Practice Patterns, Physicians{\textquoteright}, United States}, issn = {0098-7484}, author = {Psaty, B M and Koepsell, T D and Yanez, N D and Smith, N L and Manolio, T A and Heckbert, S R and Borhani, N O and Gardin, J M and Gottdiener, J S and Rutan, G H} } @article {1518, title = {The effects of measurement error in response variables and tests of association of explanatory variables in change models.}, journal = {Stat Med}, volume = {17}, year = {1998}, month = {1998 Nov 30}, pages = {2597-606}, abstract = {

Biomedical studies often measure variables with error. Examples in the literature include investigation of the association between the change in some outcome variable (blood pressure, cholesterol level etc.) and a set of explanatory variables (age, smoking status etc.). Typically, one fits linear regression models to investigate such associations. With the outcome variable measured with error, a problem occurs when we include the baseline value of the outcome variable as a covariate. In such instances, one can find a relationship between the observed change in the outcome and the explanatory variables even when there is no association between these variables and the true change in the outcome variable. We present a simple method of adjusting for a common measurement error bias that tends to be overlooked in the modelling of associations with change. Additional information (for example, replicates, instrumental variables) is needed to estimate the variance of the measurement error to perform this bias correction.

}, keywords = {Bias, Linear Models}, issn = {0277-6715}, author = {Yanez, N D and Kronmal, R A and Shemanski, L R} } @article {607, title = {Prevalence, predisposing factors, and prognosis of clinically unrecognized myocardial infarction in the elderly.}, journal = {J Am Coll Cardiol}, volume = {35}, year = {2000}, month = {2000 Jan}, pages = {119-26}, abstract = {

OBJECTIVES: This study was designed to determine the prevalence of unrecognized myocardial infarction (UMI), as well as risk factors, and to compare prognosis after detection of previously UMI to that after recognized myocardial infarction (RMI).

BACKGROUND: Past studies revealed that a significant proportion of MIs escape recognition, and that prognosis after such events is poor, but the epidemiology of UMI has not been reassessed in the contemporary era.

METHODS: The Cardiovascular Health Study (CHS) database, composed of individuals > or =65, was queried for participants who, at entry, demonstrated electrocardiographic evidence of a prior Q-wave MI, but who lacked a history of this diagnosis. The features and outcomes of this group were compared to those of individuals with prevalent RMI.

RESULTS: Of 5,888 participants, 901 evidenced a past MI, and 201 (22.3\%) were previously unrecognized. The independent predictors of UMI were the absence of angina and the absence of congestive heart failure (CHF). Six-year mortality did not significantly differ between the two groups.

CONCLUSIONS: 1) In the elderly, UMI continues to represent a significant proportion of all MIs; 2) associations with angina and CHF may reflect complex neurological issues, but they also may represent diagnosis bias; 3) these individuals can otherwise not be distinguished from those with recognized infarctions; and 4) mortality rates after UMI and RMI are similar. Future studies should address screening for UMI, risk stratification after detection of previously UMI, and the role of standard post-MI therapies.

}, keywords = {Aged, Cause of Death, Coronary Disease, Cross-Sectional Studies, Databases, Factual, Electrocardiography, Female, Follow-Up Studies, Humans, Male, Myocardial Infarction, Prognosis, Risk Factors, Stroke, Survival Rate}, issn = {0735-1097}, doi = {10.1016/s0735-1097(99)00524-0}, author = {Sheifer, S E and Gersh, B J and Yanez, N D and Ades, P A and Burke, G L and Manolio, T A} }