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Karin Rådholm, Karin Festin, Magnus Falk, Patrik Midlöv, Sigvard Mölstad, Carl Johan Östgren, Blood pressure and all-cause mortality: a prospective study of nursing home residents, Age and Ageing, Volume 45, Issue 6, 2 November 2016, Pages 826–832, https://doi.org/10.1093/ageing/afw122
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to explore the natural course of blood pressure development and its relation to mortality in a nursing home cohort.
a cohort of 406 nursing home residents in south east Sweden was followed prospectively for 30 months. Participants were divided into four groups based on systolic blood pressure (SBP) at baseline. Data were analysed using a Cox regression model with all-cause mortality as the outcome measurement; paired Student t-tests were used to evaluate blood pressure development over time.
during follow-up, 174 (43%) people died. Participants with SBP < 120 mmHg had a hazard ratio for mortality of 1.56 (95% confidence interval, 1.08–2.27) compared with those with SBP 120–139 mmHg, adjusted for age and sex. Risk of malnutrition or present malnutrition was most common in participants with SBP < 120 mmHg; risk of malnutrition or present malnutrition estimated using the Mini Nutritional Assessment was found in 78 (71%). The levels of SBP decreased over time independent of changes in anti-hypertensive medication.
in this cohort of nursing home residents, low SBP was associated with increased all-cause mortality. SBP decreased over time; this was not associated with altered anti-hypertensive treatment. The clinical implication from this study is that there is a need for systematic drug reviews in elderly persons in nursing homes, paying special attention to those with low SBP.
Introduction
The prevalence of hypertension in the population increases with age. In the Framingham Heart Study, 85% of the non-hypertensive middle-aged population at baseline developed hypertension during 20–25 years of follow-up [1]. The increase in systolic blood pressure (SBP) with age occurs due to decreased blood vessel distensibility, increased thickness of the intima media and endothelial dysfunction [2].
In the European guidelines on hypertension management, the recommended goal for hypertension treatment is less than 140/90 mmHg. However, the evidence derived from randomised controlled trials on the beneficial effects of reaching this treatment goal is scarce with regard to older patients with hypertension [3]. General practitioners (GPs) accept higher blood pressure levels than recommended in guidelines, especially in older patients [4]. In the HYVET study on patients aged 80 years or older with a blood pressure target of <150/90 mmHg, it was concluded that treatment of hypertension was also beneficial in this age group [5]. However, the effect of reaching the blood pressure treatment target was not evaluated in the frailest older people with hypertension due to exclusion criteria such as clinical dementia and the need for nursing care. The aim of this study was to assess blood pressure at baseline and prospective development of blood pressure in relation to mortality in nursing homes residents with multiple co-morbidities.
Methods
Participants were categorised into four groups according to their SBP: <120 mmHg, 120–139 mmHg, 140–159 mmHg or ≥160 mmHg. The appropriate systolic blood pressure levels in aged persons are not fully evaluated and differ between guidelines [3, 8]. We therefore used the prehypertension category (SBP 120–139 mmHg) [9] as the reference category to render both a higher and lower cut of, comparable to adult guideline recommendations. Orthostatic blood pressure was measured after standing for 1 min and an orthostatic reaction was present if there was a decrease in SBP of ≥20 mmHg or a decrease in diastolic blood pressure (DBP) of ≥10 mmHg [10]. The estimated glomerular filtration rate (eGFR) was calculated from the cystatin C value using the Grubb formula [11]. An eGFR ≥ 60 ml/min/1.73 m2 was classified as normal or mildly impaired renal function, <60 ml/min/1.73 m2 was classified as moderate renal impairment and <30 ml/min/1.73 m2 as severe renal impairment [4].
The Mini Nutritional Assessment (MNA) screening tool was used to evaluate nutritional status and the presence or risk of malnutrition. The initial sum was calculated and participants with 11 points or less were evaluated in MNA part two. All participants were classified as no risk of malnutrition, risk of malnutrition or present malnutrition [12]. Hypertensive treatment was categorised in four groups: diuretics (thiazide or aldosterone antagonists including pyrazine carbonylguanidine derivatives); angiotensin-convertingenzyme inhibitors/angiotensin receptor blockers; beta-blockers; and calcium blockers. Medications were summarised to describe the total use of anti-hypertensive drugs. Fixed combination drugs were categorised accordingly in the different medication categories.
Frailty, defined as an age-related decline of multiple physical functions [13], has previously been addressed in this cohort [6]. To evaluate frailty, we assessed accumulated deficits by a frailty index (FI) [14] that consisted of 45 different variables where the present deficits were divided by the total number of potential deficits. This is described in additional file 1.
Statistical analysis
Differences in categorical variables were analysed with Pearson's chi-squared test. Continuous variables were examined with Student's t-test or the Kruskal–Wallis test if not normally distributed. Changes in SBP over time in a subgroup of 180 participants were compared on an individual level using a paired Student's t-test. Possible associations between SBP changes during follow up and differences in antihypertensive treatment, weight loss and FI at baseline were evaluated with a linear regression analysis. Cox regression analysis was used to estimate relationships between the time of inclusion until death and SBP at inclusion and to adjust for possible confounders as, age, sex, CHF diagnosis, BMI and number of comorbidities. All remaining participants were censured at the end of the follow-up period (April 2011). Four SBP categories were included in the Cox regression model and SBP 120–139 mmHg was used as the reference group. Age was measured as a continuous variable. Statistical significance was set at P < 0.05. Data were processed using SPSS (version 22).
Ethics
The study was approved by the Regional Ethical Board in Linköping, Sweden (www.ClinicalTrials.gov number 150-07).
Results
There was a significant difference between the sexes regarding SBP; men had lower SBP compared with women (127 mmHg versus 136 mmHg, P < 0.001). There were also fewer men than women; 119 (29.3%) men versus 287 (70.7%) women. Mean age was 83 years (SD 6.6 years) for men versus 86 years (SD 6.9 years) for women. Participants had FI scores ranging between 0.08 and 0.61 with a median value of 0.39. One hundred seventy-four (42.9%) participants died during the study and because of this and the fact that continuous inclusion took place throughout the study period, only 107 (26.4%) participants had data on blood pressure measurements for the 30-month study period (Figure 1).
Mean blood pressure at baseline was 134/72 (SD 23/12) mmHg; 246 participants (60%) had SBP < 140 mmHg and 378 (93%) had DBP < 90 mmHg.
The baseline characteristics are shown in Table 1 according to SBP group. Risk of malnutrition or present malnutrition was most common in participants with SBP < 120 mmHg; 78 (71%) had risk of malnutrition or present malnutrition as estimated using MNA. BNP values and FI scores were also significantly higher in the SBP < 120 mmHg group compared with the three other SBP groups. One hundred seventy-seven participants were unable to participate in measurement of orthostatic blood pressure due to their inability to stand for 1 min; this was significantly more common in the two lowest SBP groups (data not shown).
. | SBP < 120 mmHg (n = 110) . | SBP 120–139 mmHg (n = 136) . | SBP 140–159 mmHg (n = 103) . | SBP ≥ 160 mmHg (n = 57) . | P* . | P** . |
---|---|---|---|---|---|---|
Baseline characteristics | ||||||
Sex, male, no./total no. (%) | 45/110 (40.9) | 39/136 (28.7) | 23/103 (22.3) | 12/57 (21.1) | 0.009 | 0.002 |
Age, median (IQR) | 86 (10.0) | 84 (10.0) | 84 (10.0) | 87 (9.0) | 0.097 | 0.136 |
Weight, median kg (IQR) | 63.0 (20.0) | 67.1 (22.0) | 67.1 (20.0) | 64.9 (17.0) | 0.047 | 0.036 |
Risk of malnutrition/malnutrition, no./total no. (%)a | 78/109 (71.6) | 81/134 (60.4) | 51/99 (51.5) | 31/56 (55.4) | 0.023 | 0.006 |
Present orthostatic reaction, no./total no. (%)b | 17/57 (29.8) | 22/74 (29.7) | 26/65 (40.0) | 14/33 (42.4) | 0.379 | 0.392 |
Laboratory analyses | ||||||
eGFR (cyst), median ml/min/1.73 m2 (IQR) | 57.0 (37.0) | 55.0 (37.0) | 57.0 (34.0) | 60.0 (33.0) | 0.845 | 0.662 |
BNP, median ng/l (IQR) | 159.5 (179.0) | 78.0 (119.0) | 112.0 (134.0) | 113.0 (134.0) | 0.002 | 0.001 |
Current medication | ||||||
Drugs, median no. (IQR)c | 7.0 (5.0) | 6.0 (4.8) | 7.0 (4.0) | 6.0 (4.5) | 0.003 | 0.016 |
Anti-hypertensives, median no. (IQR)d | 1.0 (1.25) | 1.0 (1.0) | 1.0 (1.0) | 0.0 (1.0) | 0.262 | 0.833 |
Beta-blockers, median no. (%) | 48 (43.6) | 45 (33.1) | 36 (35.0) | 16 (28.1) | 0.180 | 0.042 |
ACEI/ARB, no. (%) | 26 (23.6) | 26 (19.1) | 25 (24.3) | 9 (15.8) | 0.508 | 0.461 |
Calcium blockers, no. (%) | 8 (7.3) | 15 (11.0) | 11 (10.7) | 6 (10.5) | 0.766 | 0.288 |
Thiazide diuretics, no. (%) | 4 (3.6) | 11 (8.1) | 9 (8.7) | 3 (5.3) | 0.400e | 0.137 |
Aldosterone antagonists, no. (%)f | 11 (10.0) | 23 (16.9) | 10 (9.7) | 2 (3.5) | 0.043 | 0.606 |
Loop diuretics, no. (%) | 52 (47.3) | 52 (38.2) | 41 (39.8) | 14 (24.6) | 0.042 | 0.041 |
Warfarin, no. (%) | 9 (8.2) | 12 (8.8) | 7 (6.8) | 8 (14.0) | 0.476 | 0.767 |
Low-dose aspirin, no. (%) | 70 (63.6) | 70 (51.5) | 56 (54.4) | 26 (45.6) | 0.111 | 0.027 |
Medical historyg | ||||||
Hypertension, no. (%) | 21 (19.1) | 42 (30.9) | 36 (35.0) | 24 (42.1) | 0.010 | 0.003 |
Congestive heart failure, no. (%) | 25 (22.7) | 17 (12.5) | 18 (17.5) | 4 (7.0) | 0.035 | 0.019 |
Atrial fibrillation, no. (%) | 23 (20.9) | 24 (17.6) | 17 (16.5) | 11 (19.3) | 0.853 | 0.441 |
Diabetes, no. (%) | 21 (19.1) | 23 (16.9) | 19 (18.4) | 9 (15.8) | 0.943 | 0.663 |
Coronary heart disease, no. (%) | 24 (21.8) | 17 (12.5) | 10 (9.7) | 5 (8.8) | 0.032 | 0.004 |
Frailty Index score, median (IQR) | 0.41 (0.12) | 0.38 (0.12) | 0.37 (0.10) | 0.36 (0.11) | 0.036 | 0.006 |
. | SBP < 120 mmHg (n = 110) . | SBP 120–139 mmHg (n = 136) . | SBP 140–159 mmHg (n = 103) . | SBP ≥ 160 mmHg (n = 57) . | P* . | P** . |
---|---|---|---|---|---|---|
Baseline characteristics | ||||||
Sex, male, no./total no. (%) | 45/110 (40.9) | 39/136 (28.7) | 23/103 (22.3) | 12/57 (21.1) | 0.009 | 0.002 |
Age, median (IQR) | 86 (10.0) | 84 (10.0) | 84 (10.0) | 87 (9.0) | 0.097 | 0.136 |
Weight, median kg (IQR) | 63.0 (20.0) | 67.1 (22.0) | 67.1 (20.0) | 64.9 (17.0) | 0.047 | 0.036 |
Risk of malnutrition/malnutrition, no./total no. (%)a | 78/109 (71.6) | 81/134 (60.4) | 51/99 (51.5) | 31/56 (55.4) | 0.023 | 0.006 |
Present orthostatic reaction, no./total no. (%)b | 17/57 (29.8) | 22/74 (29.7) | 26/65 (40.0) | 14/33 (42.4) | 0.379 | 0.392 |
Laboratory analyses | ||||||
eGFR (cyst), median ml/min/1.73 m2 (IQR) | 57.0 (37.0) | 55.0 (37.0) | 57.0 (34.0) | 60.0 (33.0) | 0.845 | 0.662 |
BNP, median ng/l (IQR) | 159.5 (179.0) | 78.0 (119.0) | 112.0 (134.0) | 113.0 (134.0) | 0.002 | 0.001 |
Current medication | ||||||
Drugs, median no. (IQR)c | 7.0 (5.0) | 6.0 (4.8) | 7.0 (4.0) | 6.0 (4.5) | 0.003 | 0.016 |
Anti-hypertensives, median no. (IQR)d | 1.0 (1.25) | 1.0 (1.0) | 1.0 (1.0) | 0.0 (1.0) | 0.262 | 0.833 |
Beta-blockers, median no. (%) | 48 (43.6) | 45 (33.1) | 36 (35.0) | 16 (28.1) | 0.180 | 0.042 |
ACEI/ARB, no. (%) | 26 (23.6) | 26 (19.1) | 25 (24.3) | 9 (15.8) | 0.508 | 0.461 |
Calcium blockers, no. (%) | 8 (7.3) | 15 (11.0) | 11 (10.7) | 6 (10.5) | 0.766 | 0.288 |
Thiazide diuretics, no. (%) | 4 (3.6) | 11 (8.1) | 9 (8.7) | 3 (5.3) | 0.400e | 0.137 |
Aldosterone antagonists, no. (%)f | 11 (10.0) | 23 (16.9) | 10 (9.7) | 2 (3.5) | 0.043 | 0.606 |
Loop diuretics, no. (%) | 52 (47.3) | 52 (38.2) | 41 (39.8) | 14 (24.6) | 0.042 | 0.041 |
Warfarin, no. (%) | 9 (8.2) | 12 (8.8) | 7 (6.8) | 8 (14.0) | 0.476 | 0.767 |
Low-dose aspirin, no. (%) | 70 (63.6) | 70 (51.5) | 56 (54.4) | 26 (45.6) | 0.111 | 0.027 |
Medical historyg | ||||||
Hypertension, no. (%) | 21 (19.1) | 42 (30.9) | 36 (35.0) | 24 (42.1) | 0.010 | 0.003 |
Congestive heart failure, no. (%) | 25 (22.7) | 17 (12.5) | 18 (17.5) | 4 (7.0) | 0.035 | 0.019 |
Atrial fibrillation, no. (%) | 23 (20.9) | 24 (17.6) | 17 (16.5) | 11 (19.3) | 0.853 | 0.441 |
Diabetes, no. (%) | 21 (19.1) | 23 (16.9) | 19 (18.4) | 9 (15.8) | 0.943 | 0.663 |
Coronary heart disease, no. (%) | 24 (21.8) | 17 (12.5) | 10 (9.7) | 5 (8.8) | 0.032 | 0.004 |
Frailty Index score, median (IQR) | 0.41 (0.12) | 0.38 (0.12) | 0.37 (0.10) | 0.36 (0.11) | 0.036 | 0.006 |
Data are no. (%) or median (IQR). ACEI, angiotensin-converting enzyme inhibitors; ARB, angiotensin receptor blockers; BNP, brain natriuretic peptide; eGFR, estimated glomerular filtration rate; IQR, interquartile range; TSH, thyroid stimulating hormone. P-values were calculated with Student's t-test for continuous variables, or the Kruskal–Wallis test if not normally distributed, and the chi-squared test for categorical variables. *P for comparison between all groups and **P for systolic blood pressure <120 mmHg compared with ≥120 mmHg.
aRisk of malnutrition or present malnutrition was estimated using MNA part two values: <17–23.5 points (MNA part one values ≤12 points or MNA part two values >23.5 points were categorised as no risk of malnourishment).
bData on 177 participants were missing due to inability to participate.
cTotal number of drugs includes all prescribed drugs.
dIncludes beta-blockers, ACEI/ARB, calcium blockers, thiazide diuretics and aldosterone antagonists including pyrazine carbonyl guanidine derivatives (amiloride).
eP value for categorical variables with cells that had an expected count less than five was analysed with the Fisher exact test.
fAldosterone antagonists including pyrazine carbonyl guanidine derivatives (amiloride).
gData are ICD-10 classified diagnoses.
. | SBP < 120 mmHg (n = 110) . | SBP 120–139 mmHg (n = 136) . | SBP 140–159 mmHg (n = 103) . | SBP ≥ 160 mmHg (n = 57) . | P* . | P** . |
---|---|---|---|---|---|---|
Baseline characteristics | ||||||
Sex, male, no./total no. (%) | 45/110 (40.9) | 39/136 (28.7) | 23/103 (22.3) | 12/57 (21.1) | 0.009 | 0.002 |
Age, median (IQR) | 86 (10.0) | 84 (10.0) | 84 (10.0) | 87 (9.0) | 0.097 | 0.136 |
Weight, median kg (IQR) | 63.0 (20.0) | 67.1 (22.0) | 67.1 (20.0) | 64.9 (17.0) | 0.047 | 0.036 |
Risk of malnutrition/malnutrition, no./total no. (%)a | 78/109 (71.6) | 81/134 (60.4) | 51/99 (51.5) | 31/56 (55.4) | 0.023 | 0.006 |
Present orthostatic reaction, no./total no. (%)b | 17/57 (29.8) | 22/74 (29.7) | 26/65 (40.0) | 14/33 (42.4) | 0.379 | 0.392 |
Laboratory analyses | ||||||
eGFR (cyst), median ml/min/1.73 m2 (IQR) | 57.0 (37.0) | 55.0 (37.0) | 57.0 (34.0) | 60.0 (33.0) | 0.845 | 0.662 |
BNP, median ng/l (IQR) | 159.5 (179.0) | 78.0 (119.0) | 112.0 (134.0) | 113.0 (134.0) | 0.002 | 0.001 |
Current medication | ||||||
Drugs, median no. (IQR)c | 7.0 (5.0) | 6.0 (4.8) | 7.0 (4.0) | 6.0 (4.5) | 0.003 | 0.016 |
Anti-hypertensives, median no. (IQR)d | 1.0 (1.25) | 1.0 (1.0) | 1.0 (1.0) | 0.0 (1.0) | 0.262 | 0.833 |
Beta-blockers, median no. (%) | 48 (43.6) | 45 (33.1) | 36 (35.0) | 16 (28.1) | 0.180 | 0.042 |
ACEI/ARB, no. (%) | 26 (23.6) | 26 (19.1) | 25 (24.3) | 9 (15.8) | 0.508 | 0.461 |
Calcium blockers, no. (%) | 8 (7.3) | 15 (11.0) | 11 (10.7) | 6 (10.5) | 0.766 | 0.288 |
Thiazide diuretics, no. (%) | 4 (3.6) | 11 (8.1) | 9 (8.7) | 3 (5.3) | 0.400e | 0.137 |
Aldosterone antagonists, no. (%)f | 11 (10.0) | 23 (16.9) | 10 (9.7) | 2 (3.5) | 0.043 | 0.606 |
Loop diuretics, no. (%) | 52 (47.3) | 52 (38.2) | 41 (39.8) | 14 (24.6) | 0.042 | 0.041 |
Warfarin, no. (%) | 9 (8.2) | 12 (8.8) | 7 (6.8) | 8 (14.0) | 0.476 | 0.767 |
Low-dose aspirin, no. (%) | 70 (63.6) | 70 (51.5) | 56 (54.4) | 26 (45.6) | 0.111 | 0.027 |
Medical historyg | ||||||
Hypertension, no. (%) | 21 (19.1) | 42 (30.9) | 36 (35.0) | 24 (42.1) | 0.010 | 0.003 |
Congestive heart failure, no. (%) | 25 (22.7) | 17 (12.5) | 18 (17.5) | 4 (7.0) | 0.035 | 0.019 |
Atrial fibrillation, no. (%) | 23 (20.9) | 24 (17.6) | 17 (16.5) | 11 (19.3) | 0.853 | 0.441 |
Diabetes, no. (%) | 21 (19.1) | 23 (16.9) | 19 (18.4) | 9 (15.8) | 0.943 | 0.663 |
Coronary heart disease, no. (%) | 24 (21.8) | 17 (12.5) | 10 (9.7) | 5 (8.8) | 0.032 | 0.004 |
Frailty Index score, median (IQR) | 0.41 (0.12) | 0.38 (0.12) | 0.37 (0.10) | 0.36 (0.11) | 0.036 | 0.006 |
. | SBP < 120 mmHg (n = 110) . | SBP 120–139 mmHg (n = 136) . | SBP 140–159 mmHg (n = 103) . | SBP ≥ 160 mmHg (n = 57) . | P* . | P** . |
---|---|---|---|---|---|---|
Baseline characteristics | ||||||
Sex, male, no./total no. (%) | 45/110 (40.9) | 39/136 (28.7) | 23/103 (22.3) | 12/57 (21.1) | 0.009 | 0.002 |
Age, median (IQR) | 86 (10.0) | 84 (10.0) | 84 (10.0) | 87 (9.0) | 0.097 | 0.136 |
Weight, median kg (IQR) | 63.0 (20.0) | 67.1 (22.0) | 67.1 (20.0) | 64.9 (17.0) | 0.047 | 0.036 |
Risk of malnutrition/malnutrition, no./total no. (%)a | 78/109 (71.6) | 81/134 (60.4) | 51/99 (51.5) | 31/56 (55.4) | 0.023 | 0.006 |
Present orthostatic reaction, no./total no. (%)b | 17/57 (29.8) | 22/74 (29.7) | 26/65 (40.0) | 14/33 (42.4) | 0.379 | 0.392 |
Laboratory analyses | ||||||
eGFR (cyst), median ml/min/1.73 m2 (IQR) | 57.0 (37.0) | 55.0 (37.0) | 57.0 (34.0) | 60.0 (33.0) | 0.845 | 0.662 |
BNP, median ng/l (IQR) | 159.5 (179.0) | 78.0 (119.0) | 112.0 (134.0) | 113.0 (134.0) | 0.002 | 0.001 |
Current medication | ||||||
Drugs, median no. (IQR)c | 7.0 (5.0) | 6.0 (4.8) | 7.0 (4.0) | 6.0 (4.5) | 0.003 | 0.016 |
Anti-hypertensives, median no. (IQR)d | 1.0 (1.25) | 1.0 (1.0) | 1.0 (1.0) | 0.0 (1.0) | 0.262 | 0.833 |
Beta-blockers, median no. (%) | 48 (43.6) | 45 (33.1) | 36 (35.0) | 16 (28.1) | 0.180 | 0.042 |
ACEI/ARB, no. (%) | 26 (23.6) | 26 (19.1) | 25 (24.3) | 9 (15.8) | 0.508 | 0.461 |
Calcium blockers, no. (%) | 8 (7.3) | 15 (11.0) | 11 (10.7) | 6 (10.5) | 0.766 | 0.288 |
Thiazide diuretics, no. (%) | 4 (3.6) | 11 (8.1) | 9 (8.7) | 3 (5.3) | 0.400e | 0.137 |
Aldosterone antagonists, no. (%)f | 11 (10.0) | 23 (16.9) | 10 (9.7) | 2 (3.5) | 0.043 | 0.606 |
Loop diuretics, no. (%) | 52 (47.3) | 52 (38.2) | 41 (39.8) | 14 (24.6) | 0.042 | 0.041 |
Warfarin, no. (%) | 9 (8.2) | 12 (8.8) | 7 (6.8) | 8 (14.0) | 0.476 | 0.767 |
Low-dose aspirin, no. (%) | 70 (63.6) | 70 (51.5) | 56 (54.4) | 26 (45.6) | 0.111 | 0.027 |
Medical historyg | ||||||
Hypertension, no. (%) | 21 (19.1) | 42 (30.9) | 36 (35.0) | 24 (42.1) | 0.010 | 0.003 |
Congestive heart failure, no. (%) | 25 (22.7) | 17 (12.5) | 18 (17.5) | 4 (7.0) | 0.035 | 0.019 |
Atrial fibrillation, no. (%) | 23 (20.9) | 24 (17.6) | 17 (16.5) | 11 (19.3) | 0.853 | 0.441 |
Diabetes, no. (%) | 21 (19.1) | 23 (16.9) | 19 (18.4) | 9 (15.8) | 0.943 | 0.663 |
Coronary heart disease, no. (%) | 24 (21.8) | 17 (12.5) | 10 (9.7) | 5 (8.8) | 0.032 | 0.004 |
Frailty Index score, median (IQR) | 0.41 (0.12) | 0.38 (0.12) | 0.37 (0.10) | 0.36 (0.11) | 0.036 | 0.006 |
Data are no. (%) or median (IQR). ACEI, angiotensin-converting enzyme inhibitors; ARB, angiotensin receptor blockers; BNP, brain natriuretic peptide; eGFR, estimated glomerular filtration rate; IQR, interquartile range; TSH, thyroid stimulating hormone. P-values were calculated with Student's t-test for continuous variables, or the Kruskal–Wallis test if not normally distributed, and the chi-squared test for categorical variables. *P for comparison between all groups and **P for systolic blood pressure <120 mmHg compared with ≥120 mmHg.
aRisk of malnutrition or present malnutrition was estimated using MNA part two values: <17–23.5 points (MNA part one values ≤12 points or MNA part two values >23.5 points were categorised as no risk of malnourishment).
bData on 177 participants were missing due to inability to participate.
cTotal number of drugs includes all prescribed drugs.
dIncludes beta-blockers, ACEI/ARB, calcium blockers, thiazide diuretics and aldosterone antagonists including pyrazine carbonyl guanidine derivatives (amiloride).
eP value for categorical variables with cells that had an expected count less than five was analysed with the Fisher exact test.
fAldosterone antagonists including pyrazine carbonyl guanidine derivatives (amiloride).
gData are ICD-10 classified diagnoses.
Apart from the use of loopdiuretics, which was more common in participants with SBP < 120 mmHg than in those with higher SBP, there were no differences in pharmaceutical treatment between the SBP groups. Two hundred twenty-three (55%) participants were on low-dose aspirin. The use of aspirin was significantly more common in participants with SBP < 120 mmHgcompared with SBP ≥ 120 mmHg. There was no significant difference in statin treatment between the SBP categories. Only six participants were on non-steroidal anti-inflammatory drugs (NSAIDs), not in Table 1.
A diagnosis of hypertension was most common in participants with SBP > 160 mmHg compared with those with lower SBP. In contrast, congestive heart failure and coronary heart disease were more common in those with SBP < 120 mmHg than in the higher SBP categories. There was no difference regarding a dementia diagnosis, which was a common condition overall.
The major cause of death was CVD (including stroke) n = 77 (48%) cases. Other causes of death were infectious disease, n = 29 (18%), frailty, n = 17 (11%) and dementia, n = 15 (9%). There was no significant difference in the distribution of CVD deaths between blood pressure groups (P = 0.08), not in table.
SBP decreased during the prospective study period in a subgroup of 180 participants who were eligible for measurements over 18 months from a mean of 135 mmHg (SD 22.4) to 130 mmHg (SD 21.0, P < 0.001). This was not associated with changes in anti-hypertensive treatment (OR, −0.08 [95% CI, −8.04 to 2.48] P = 0.299), weight loss (OR, 0.085 [95% CI, −0.16 to 0.60] P = 0.264) or FI (OR, 0.31 [95% CI, −27.63 to 42.33] P = 0.679), data not shown.
Discussion
Low SBP was associated with increased mortality in elderly individuals living in nursing homes. Furthermore, SBP declined over time, which could not be explained by changes in the use of blood pressure lowering medications. Participants were frail by definition of FI in comparison with previous studies [15, 16], the study participants in the SBP group <120 mmHg significantly more so than other SBP groups.
Previous longitudinal studies have shown different outcomes for blood pressure development in aged participants; either a decrease of both SBP and DBP with advanced age or a decrease only in DBP and not SBP with the latter increasing linearly up to age 84 years [17–20]. Increased SBP is generally a risk factor for cardiovascular disease, dementia and increased mortality [19]. In advanced age, SBP < 120 mm Hg has previously been shown to be associated with increased mortality [21–24]. A large longitudinal study of persons 80 years old or older, living in nursing homes showed that the subgroup with low SBP (<130 mmHg) receiving two or more antihypertensives had a greater than 2-fold risk for mortality [25]. However, the increased risk for all-cause mortality in participants with SBP < 120 mmHg observed in our study did not change when adjusted for number of antihypertensive medications or, two or more antihypertensives. Previous studies have shown an association between low SBP and greater prevalence of dementia [26,27], which was not evident in this study because diagnosis and treatment for dementia were common and not associated with SBP. We were able to confirm from previous reports that older women have higher mean SBP than older men [21].
A low SBP in older age groups could be a marker of increasing vascular frailty; a biological process naturally linked to the ageing body, or associated with general deterioration in health with age. Several age-related factors affect SBP. Arterial stiffness and baroreceptor insensitivity are major factors [28]; the latter increases the sensitivity of blood pressure lowering drugs and the risk of postural hypotension. In addition, dehydration, hypovolaemia and electrolyte disturbances can occur with diuretics [2]. Drug effects and metabolism alter with ageing due to changes in body fat and water volume, reduced renal function, impaired ability to excrete metabolised drugs and, to some extent, altered liver function and reduced capacity for metabolising drugs [2,29]. Treatment with diuretics, especially loop diuretics, is one of the major causes of adverse drug reactions and hospital admission in older persons [30]. Furthermore, anti-hypertensive treatment is associated with increased risk of falls and there is evidence that withdrawal of anti-hypertensive drugs and other medications associated with increased risk of falls can reduce the incidence of falls in older persons [30]. Therefore, clinicians should strive to reduce the use of unnecessary drugs in older people, loop diuretics in particular.
In our study, the use of blood pressure lowering drugs was not more common in patients with SBP > 160 mmHg than in those with lower blood pressure. However, the HR for mortality in participants with SBP ≥ 160 mmHg was not increased compared with the SBP 120–139 mmHg group. There were no observed differences in mortality between SBP groups: 120–139 mmHg, 140–159 mmHg and ≥160 mmHg. The use of loop diuretics was most common in the SBP < 120 mmHg group, as was a heart failure diagnosis. Heart failure requires more intensive pharmacological treatment, with blood pressure lowering effects. However, it is doubtful whether preventive cardiovascular treatment in severely ill nursing home patients is beneficial for this population where 11% were given statins and 55% were using low-dose aspirin. Also, there were no significant differences in preventive treatments between the SBP groups. Use of NSAIDs has many known adverse effects in older people, including worsening of heart failure and risk of bleeding [29]. However, use of an NSAID analgesic was uncommon in our study (only 1.5%).
Strengths of the studyare the homogeneity of the study population located in nursing homes in various parts of Sweden, diminishing possible differences due to treatment traditions, and the continuity of the trained research nurses that performed the data collection. The high mortality rate and continuous inclusion during the study period, which meant that very few participants could be followed for the whole 30 months, are limitations of this study. The use of aneroid sphygmomanometers could pose a further limitation due to inaccurate readings. Sphygmanometers of high quality and multiple standardised measurements were used to minimise potential inaccuracies. From this observational study, it is not possible to draw conclusions about causality between the association of low SBP and mortality. Furthermore, the observed outcome may be due to reverse causation, i.e. pre-existing illness may explain both low blood pressure and impending death.
Conclusions
We conclude that low SBP was associated with increased mortality in an aged population with multiple co-morbidities residing in nursing homes. Furthermore, SBP decreased over time. A clinical implication from this study is that there is a need for systematic drug reviews in older persons in nursing homes, paying special attention to those with low SBP. Future research needs include drug intervention studies on anti-hypertensive medications in the nursing home setting.
Low SBP is associated with increased all-cause mortality in nursing home residents.
There is a need for systematic drug reviews in elderly persons in nursing homes.
SBP decreases over time; without association to altered anti-hypertensive treatment, weight loss or FI score at inclusion.
Supplementary data
Supplementary data mentioned in the text are available to subscribers in Age and Ageing online.
Acknowledgements
We would like to thank all the participants who took part in the SHADES study and the research nurses who were active in data collection, especially Christina Lannering. Many thanks also to associate professor Marie Ernsth Bravell for valuable advice on frailty.
Conflicts of interest
None declared.
Funding
This work was supported by grants from the Health Research Council in south east Sweden (FORSS-8888, FORSS-11636 and FORSS-31811), the County of Östergötland (LIO-11877, LIO-31321 and LIO-79951), the Family JanneElgqvist Foundation and King Gustaf V and Queen Victoria Freemason Foundation.
References
The Swedish Council on Technology Assessmentin Health Care: Summary and conclusions of the SBU Report: How can drug consumption among elderly be improved? A systematic review: May 2009, Rapportnr: 193, ISBN 978-91-85413-27-0, ISSN 1400-1403, in Swedish, 2009.
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