Aging, Resting Pulse Rate, and Longevity

Jochanan Stessman, MD; Jeremy M. Jacobs, MBBS; Irit Stessman-Lande, BMedSci; Dan Gilon, MD; David Leibowitz, MD

Disclosures

J Am Geriatr Soc. 2013;61(1):40-45. 

In This Article

Methods

Study Sample

The Jerusalem Longitudinal Cohort Study has followed a birth cohort of Jerusalem residents (born June 1920 to May 1921) from age 70 at baseline in 1990. A detailed description of study methodology has been reported previously.[19–21] At Phase I (1990–1991, age 70), Phase II (1997–1998, age 78), and Phase III (2005–2006, age 85), 453, 856, and 1,044 participants, respectively, were enrolled. The Phase I study sample was augmented at Phases II and III with new participants randomly recruited from the same birth cohort.

The study sample, which formed approximately one-third of the total birth cohort, was randomly selected from the electoral registry (a complete register of Jerusalem residents, born 1920–1921). The representative nature of the study sample was confirmed by finding similar rates of hospital in-patient morbidity, health service utilization and mortality, subjects who refused, and those not approached to enroll. Furthermore, no significant differences existed for comorbidity or subsequent mortality rates in subjects of the same age who entered the study at different phases. Proxy informants, with consent from legal guardians, were used in the case of participants who were extremely frail or had dementia. Each participant, or legal guardian, provided informed consent, and the Hadassah Hebrew University Medical Center institutional review board approved the study.

Measures and Data Collection

The study instrument was a previously validated two-part questionnaire, performed by interview at home, which offered respondents graded multiple-choice answers.[19] A nurse or occupational therapist administered the first part of the questionnaire, and data were collected concerning detailed demographic characteristics, personal history, lifestyle, health services utilization, function, and cognitive status. Physicians administered the second part, which involved a thorough medical history and examination, including extensive review of systems.

Resting Pulse Rate

The examining physician measured pulse rate by palpation of the radial artery for 60 seconds at 2-minute intervals after 5 minutes of sitting. Subjects with a history of pacemaker implantation (n = 42) were excluded from the study.

Study Measures

Sitting blood pressure with the arm supported at heart level was measured three times using a validated electronic sphygmomanometer (Omron 705IT, Omron Corporation, Kyoto, Japan) at both home visits, and the average was calculated. Hypertension was defined as treatment with antihypertensive medications or blood pressure higher than 140 mmHg systolic or 90 mmHg diastolic. All subjects receiving antihypertension medication were defined as having hypertension. All medications, including beta blockers, were recorded according to class. Diagnosis of ischemic heart disease (IHD) was the composite of history of hospitalization for myocardial infarction (MI) or an acute coronary syndrome, coronary catheterization with evidence of a significant coronary artery disease, MI on electrocardiogram, a history typical of angina pectoris on exertion, and previous coronary revascularization. Diabetes mellitus was defined according to physician diagnosis. The study physician made diagnoses after medical assessment, system review, and examination. Major diseases were defined according to the International Classification of Diseases, Ninth Revision.[22] Charlson Comorbidity Index was determined, with high defined as greater than 3.[23]

Self-rated health was evaluated using the question: "Do you feel healthy in comparison to people your age?" Functional status was defined as dependence on another person in one or more of six activities of daily living (ADLs; transfer, dressing, bathing, hygiene in the toilet, eating, and continence).[24] Depression was determined using the Brief Symptom Inventory.[25] The Mini-Mental State Examination was administered.[26] Smoking was defined as current cigarette pack-years. Body mass index was determined as weight in kilograms divided by square of height in meters.

Physical Activity Level

To assess level of physical activity, subjects were asked: "How often are you physically active?" (<4 h/wk; ≥ ~4 h/wk; regular physical activity, e.g., walking ≥1 h/d; vigorous sports at least twice weekly, e.g., jogging, swimming). Physical activity was dichotomized as sedentary (answer 1) vs physically active (answers 2, 3, or 4). This four-item questionnaire was adapted from the Gothenburg population study of 70-year-olds, and this cutoff point has been shown to predict mortality and functional decline in the current study cohort.[27] The questionnaire measured current levels of physical activity at the time of questioning and did not account for previous levels.

Outcomes

Death was the primary outcome throughout the study period from 1990 to 2010. Mortality data were obtained from annual review of all obligatory notifications of death issued by the Ministry of Interior throughout the study period (1990–2010). This method provided 100% surveillance of mortality data for subjects remaining in Israel.

Statistical Analysis

Descriptive statistics were performed, and results are described as means and standard deviations for normally distributed data. Percentages were calculated as appropriate. Differences between means were calculated using t-tests for continuous variables and chi-square tests for categorical variables. Kaplan–Meier survival curves were determined and the log rank test was performed to examine RPR as a dichotomous variable (< or >80 bpm). RPR was examined as a continuous variable in Cox proportional hazard models. Hazard ratios (HRs) for mortality were determined after adjusting for sex, level of education, diabetes mellitus, IHD, congestive heart failure, hypertension, clinical history of renal disease, anemia, self-rated health, body mass index, and dementia. Level of physical activity, beta-blocker therapy, and the interaction variable of RPR by beta-blocker were also adjusted for. All P-values were two-tailed, and P < .05 was considered to be significant. The data storage and analysis was performed using SAS version 9.1e (SAS Institute, Inc., Cary, NC).

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