Abstract
This study compares rates of injurious falls and syncope in community-dwelling older adults in the Irish Longitudinal Study on Ageing with rates in the Systolic Blood Pressure Intervention Trial.
The Systolic Blood Pressure Intervention Trial (SPRINT) demonstrated that treating adults 75 years of age or older with hypertension to reach a systolic blood pressure target of less than 120 mm Hg compared with a systolic blood pressure target of less than 140 mm Hg reduced the numbers of cardiovascular events and death without a significant increase in the number of injurious falls or syncope. However, prior to the adoption of an intensive strategy to lower systolic blood pressure in the oldest segment of the population, it is prudent to determine if individuals meeting inclusion criteria for SPRINT outside the clinical trial context are similar to trial participants, especially with regard to risk for adverse outcomes. We used The Irish Longitudinal Study on Ageing (TILDA) to compare baseline rates of injurious falls and syncope in community-dwelling older adults with the rates in the standard care group of SPRINT.
Methods
The Irish Longitudinal Study on Ageing is a nationally representative prospective cohort study of community-dwelling adults 50 years of age or older in the Republic of Ireland. Random sampling of geographical clusters was used to select households. Data collection involved an in-home interview, a self-completed questionnaire (N = 8175), and a comprehensive health assessment (N = 5751). Mean follow-up for TILDA was 3.4 years, compared with a median of 3.4 years in SPRINT. Our study used data from wave 1 of TILDA (completed July 31, 2011) to retrospectively identify participants meeting final inclusion criteria for SPRINT. Outcomes were then reported at wave 2 (February 1, 2012-March 31, 2013) and wave 3 (March 1, 2014-December 31, 2015) follow-up. Ethical approval for TILDA was obtained from the Faculty of Health Sciences Research Ethics Committee at Trinity College Dublin. All participants provided written informed consent.
We used the SPRINT eligibility criteria to identify TILDA participants who would be eligible for the trial.; all SPRINT eligibility parameters apart from degree of proteinuria were available for TILDA participants. Falls and syncope were assessed either by self-report or proxy at each wave. Participants were asked if they had fallen since their last interview and, if so, if they injured themselves seriously enough to need medical treatment. These questions were repeated for syncope. All analyses were performed using R statistical software (R Foundation for Statistical Computing) and Stata, version 14.1 (StataCorp), incorporating inverse probability weighting to account for complex survey designs. P < .05 was considered significant.
Results
The Table displays a comparison of characteristics between TILDA participants meeting inclusion criteria for the subgroup of SPRINT participants who were 75 years of age or older and those of participants in the standard care arm of SPRINT. All 407 participants in TILDA were white, as opposed to participants in SPRINT (987 of 1319 [74.8%]). Orthostatic hypotension at baseline was more common in TILDA participants than SPRINT (50 of 407 [12.3%] vs 124 of 1319 [9.4%]). History of cardiovascular disease (309 of 1319 [23.4%] vs 72 of 407 [17.7%]), as well as rates of aspirin (765 of 1319 [58.0%] vs 160 of 407 [39.3%]) and statin use (697 of 1319 [52.8%] vs 159 of 407 [39.1%]), were higher in SPRINT participants, suggesting a higher cardiovascular risk profile. While the 407 TILDA participants were undergoing standard care in the community for a similar duration of follow-up, 111 (27.3%) reported an injurious fall and 54 (13.3%) reported syncope. In SPRINT, 73 of 1319 participants (5.5%) reported injurious falls and 32 of 1319 (2.4%) reported syncope (Figure).
Table. Characteristics of Community-Dwelling TILDA Participants Meeting SPRINT Inclusion Criteria vs SPRINT Participants.
| Characteristic | TILDA Participants Aged ≥75 y Meeting Inclusion Criteria for SPRINT (N = 407) |
SPRINT Participants Aged ≥75 y (N = 1319) |
|---|---|---|
| Female sex, No. (%) | 239 (58.7) | 501 (38.0) |
| Age, mean (SD), y | 80.1 (6.1) | 79.9 (4.1) |
| Race/ethnicity, No. (%) | ||
| White | 100 | 987 (74.8) |
| Black or African American | 0 | 226 (17.1) |
| Hispanic | 0 | 85 (6.4) |
| Other | 0 | 21 (1.6) |
| Seated blood pressure, mean (SD), mm Hg | ||
| Systolic | 148.1 (14.1) | 141.6 (15.8) |
| Diastolic | 82.0 (10.1) | 70.9 (11.0) |
| Orthostatic hypotension, No. (%)a | ||
| No | 357 (87.7) | 1195 (90.6) |
| Yes | 50 (12.3) | 124 (9.4) |
| Serum creatinine, median (IQR), mg/dLb | 0.94 (0.81-1.12) | 1.1(0.9-1.3) |
| Estimated GFR, mean (SD), mL/min/1.73 m2c | 65.1 (19.9) | 63.3 (18.3) |
| History of cardiovascular disease, No. (%) | ||
| No | 335 (82.3) | 1010 (76.6) |
| Yes | 72 (17.7) | 309 (23.4) |
| Statin use, No. (%) | ||
| No | 248 (60.9) | 622 (47.2) |
| Yes | 159 (39.1) | 697 (52.8) |
| Aspirin use, No. (%) | ||
| No | 247 (60.7) | 554 (42.0) |
| Yes | 160 (39.3) | 765 (58.0) |
| Total cholesterol, mean (SD), mg/dLd | 185.3 (38.6) | 181.8 (38.7) |
| Triglycerides, mean (SD), mg/dLd | 137.2 (84.0) | 99.0 (72.0-134.5)e |
| HDL cholesterol, mean (SD), mg/dLd | 59.5 (17.4) | 55.7 (14.9) |
| Body mass index, mean (SD)f | 28.0 (5.0) | 27.7 (4.6) |
| Gait speed, median (IQR), m/sg,h | 1.17 (1.05-1.32) | 0.92 (0.77-1.06) |
| >0.8 m/s, No. (%) | 389 (95.5) | 950 (72.0) |
| <0.8 m/s, No. (%) | 18 (4.5) | 369 (28.0) |
| Frailty, No. (%)i | ||
| Not frail (TILDA) or fit (SPRINT) | 147 (36.1) | 190 (14.4) |
| Prefrail (TILDA) or less fit (SPRINT) | 221 (54.3) | 745 (56.5) |
| Frail | 39 (9.6) | 375 (28.4) |
Abbreviations: GFR, glomerular filtration rate; HDL, high-density lipoprotein; IQR, interquartile range; SPRINT, Systolic Blood Pressure Intervention Trial; TILDA, The Irish Longitudinal Study on Ageing.
SI conversion factors: To convert creatinine to micromoles per liter, multiply by 88.4; to convert total and HDL cholesterol to millimoles per liter, multiply by 0.0259; and to convert triglycerides to millimoles per liter, multiply by 0.0113.
Criterion for orthostatic hypotension was a decrease in systolic blood pressure of 20 mm Hg or more or a decrease in diastolic blood pressure of 10 mm Hg or more after standing.
A total of 55 participants were missing data.
Estimated using Modification of Diet in Renal Disease.
A total of 30 participants were missing data.
Reported as median (IQR).
Calculated as weight in kilograms divided by height in meters squared.
A total of 160 participants were missing data.
In TILDA, gait speed was measured using GAITRite portable electronic walkway system (CIR Systems Inc). Participants were instructed to walk at their usual pace along a 4.88-m walkway. They started walking 2.5 m before the walkway to allow for acceleration and finished walking 2 m after the walkway to allow for deceleration. The mean gait speed from 2 walks was recorded in units of centimeters per second. In SPRINT, gait speed was measured via a timed 4-m walk performed at the participant’s usual pace from a standing start.
Frailty in TILDA determined by Freid criteria; frailty in SPRINT determined by SPRINT-specific frailty index.
Figure. Comparison of the Prevalence Rates of Injurious Falls and Syncope Between the Systolic Blood Pressure Intervention Trial (SPRINT) and The Irish Longitudinal Study on Ageing (TILDA) Participants 75 Years or Older.
Outcome prevalence is reported while also accounting for the attrition rate over the course of the study. Between wave 1 and wave 2 of TILDA, 46 of 407 participants (11.3%) were no longer participating in the study owing to death (n = 21), loss to follow-up (n = 2), refusal to answer questions as part of the study (n = 22), or withdrawal from the study (n = 1). Between wave 2 and wave 3, 109 of 407 participants (26.8%) were no longer participating in the study. Ascertainment of the reasons for this attrition at wave 3 is currently still ongoing at the time of writing.
Discussion
In a community-based prospective cohort with contemporaneous follow-up of comparable duration (TILDA), participants 75 years of age or older who met inclusion criteria for SPRINT had rates of injurious falls and syncope approximately 5-fold higher than the standard care group in SPRINT. Given the high baseline rates of falls and syncope, any increase in these rates due to intensive treatment of hypertension could result in harm.
References
- 1.Williamson JD, Supiano MA, Applegate WB, et al. ; SPRINT Research Group . Intensive vs standard blood pressure control and cardiovascular disease outcomes in adults aged ≥75 years: a randomized clinical trial. JAMA. 2016;315(24):2673-2682. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Finucane C, O’Connell MD, Fan CW, et al. Age-related normative changes in phasic orthostatic blood pressure in a large population study: findings from The Irish Longitudinal Study on Ageing (TILDA). Circulation. 2014;130(20):1780-1789. [DOI] [PubMed] [Google Scholar]
- 3.Finucane C, O’Connell MDL, Donoghue O, Richardson K, Savva GM, Kenny RA. Impaired orthostatic blood pressure recovery is associated with unexplained and injurious falls. J Am Geriatr Soc. 2017;65(3):474-482. [DOI] [PubMed] [Google Scholar]
- 4.Bress AP, Tanner RM, Hess R, Colantonio LD, Shimbo D, Muntner P. Generalizability of SPRINT results to the US adult population. J Am Coll Cardiol. 2016;67(5):463-472. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Fried LP, Tangen CM, Walston J, et al. ; Cardiovascular Health Study Collaborative Research Group . Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci. 2001;56(3):M146-M156. [DOI] [PubMed] [Google Scholar]