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The Journals of Gerontology Series A: Biological Sciences and Medical Sciences 55:M667-M671 (2000)
© 2000 The Gerontological Society of America

Variability of Blood Pressure Response to Orthostatism and Reproducibility of the Diagnosis of Orthostatic Hypotension in Elderly Subjects

Joël Belmina, Malika Abderrhamanea, Smahane Medjaheda, Joyce Sibony-Prata, Anne Bruhata, Nicolas Bojica and Thierry Marqueta

a Department of Médecine Interne Gériatrique, Hôpital René Muret-Bigottini and University Paris-Nord, Sevran, France

Joël Belmin, Service de Médecine Interne Gériatrique, Hôpital René Muret-Bigottini and Université Paris-Nord, Avenue du Dr Schaëffner, 93270 Sevran, France E-mail: joel.belmin{at}rmb.ap-hop-paris.fr.

William B. Ershler, MD


   Abstract
Top
 Abstract
Methods
 Results
 Discussion
 References
 
Background.

Orthostatic hypotension (OH) is a major problem in the elderly population. Its diagnosis is based on measurement of the blood pressure (BP) response to orthostatism (BPRO). This study investigates the within-day and day-to-day variability of the BPRO and the reproducibility of the diagnosis of OH in this population.

Methods.

BP was measured in the supine position and after 1 and 2 minutes of orthostatism in 53 consecutive elderly patients (43 women and 10 men aged 83.7 ± 9.5 years) of an intermediate care geriatric ward. BPRO was assessed 4 times on the same day (8–9 AM, 10–11 AM, 1–2 PM, and 5–6 PM) and twice more on another day of the same week (8–9 AM and 1–2 PM).

Results

There were significant within-day differences between the four orthostatic changes in systolic BP (OCs, supine minus standing systolic BP) after 1 minute or 2 minutes (p < .05). Day-to-day differences between the OCs measured at the same times were not significant. OH defined as an OCs of 20 mm Hg or more at 1 or 2 minutes of orthostatism, was found in ten cases (19%) in the initial set of measurements on the first day. A cumulative diagnosis of OH after the six BPRO tests was found in 23 cases (43%). The reproducibility of the diagnosis of OH was mild or poor (all kappa values were below 0.47).

Conclusions.

BPRO exhibits significant within-day variability in elderly patients. Within-day and day-to-day reproducibility of the diagnosis of OH, based on conventional criteria, were found to be poor.

ORTHOSTATIC hypotension (OH) is a major health problem in elderly persons. It is extremely common in older individuals and affects from 10% to 33% of community-dwelling people of 65 years and older and much larger proportions among elderly institutionalized patients (1)(2)(3)(4)(5)(6). OH is responsible for disabling symptoms that can cause dizziness, falls, and several complications, including motor dependency, hospitalizations, impaired quality of life and/or vital complications (4)(6)(7). A number of conditions that are common in elderly persons are responsible for OH (4)(8). In particular, several drugs frequently prescribed for elderly persons may impair the regulation of blood pressure (BP) in orthostatism (9)(10)(11). Thus, careful measurement of the BP response during orthostatism (BPRO) is widely recommended to permit detection of asymptomatic drug-induced OH and prevent symptomatic OH and its complications (10)(11).

The diagnosis of OH is based on measurement of the BP response to the change from the supine to the standing position. Several authors consider that this diagnosis is defined by an orthostatic change in systolic BP (OCs, supine minus standing systolic BP) of 20 mm Hg or more (12)(13). Others used the same change and/or a decline of 10 mm Hg or more in diastolic BP as diagnosis criteria. To our knowledge, the reproducibility of the diagnosis has not been extensively studied. In a preliminary study of 40 elderly patients with documented and symptomatic OH, Ward and Kenny (12) found that 13 of them (33%) did not exhibit an OCs of 20 mm Hg or more when a second measurement was made in the same morning. Their results suggest that the reproducibility of OH diagnosis might be poor. Another study of a large nursing home population showed that the prevalence of OH varied, depending on the timing of measurements (13). The present study assesses the within-day and day-to-day variability of orthostatic BP changes and their consequences on the diagnosis of OH in unselected elderly patients in an intermediate care ward.


   Methods
Top
 Abstract
 Methods
Results
 Discussion
 References
 
Patients
All the patients in an intermediate care unit of a French geriatric hospital were screened to participate in the study. Patients were eligible if they were able to transfer from bed to standing and stay upright, had no unstable medical conditions such as dehydration, heart failure, renal failure, current infection, and current atrial fibrillation, and gave consent to have repeated BP measurements. None of their drug regimens were changed for the study. In particular, drug therapy was not modified during the period of BP measurements or the previous week. All medication given to patients on the days of BP measurements was recorded.

BP Measurements
BP was measured on the participant's nondominant arm by one of the authors (MA) using an automatized oscillometric monitor (Dinamap, Critikon, Tampa, FL) to avoid any bias connected with the observer. Supine BP was measured at the bedside, after patients had rested for 10 minutes or more in a quiet atmosphere. Three successive measurements were done to ensure that resting supine BP was stable and to accustom patients to the automatic device. The last measure was the one considered for the study. Then, standing BP was measured after 1 and 2 minutes of orthostatism. Results were printed for subsequent analysis.

Variability of BP Response to Orthostatism
Within-day variability of the BPRO was assessed by measuring BP 4 times during the same day: between 8 and 9 AM, before any drug intake or breakfast; between 10 and 11 AM; between 1 and 2 PM, after lunch; and between 5 and 6 PM, before dinner. Day-to-day variability was determined by twice assessing BPRO on a 2nd day, randomly selected among the 5 following days: between 8 and 9 AM and between 1 and 2 PM.

Diagnosis of OH
An OCs (supine minus standing systolic BP) of 20 mm Hg or more was used to diagnose OH (12)(13). For the purposes of the study, changes at 1 and 2 minutes were considered separately; the largest of the two changes was also considered. We also analyzed the measurements using another definition of OH (i.e., a decline of 20 mm Hg or more in systolic BP and/or a decline of 10 mm Hg or more in diastolic BP during 1 or 2 minutes of orthostatism).

Statistical Analysis
Within-day and day-to-day variability in the BP level and in BP responses to orthostatism were assessed by one-factor repeated measures analysis of variance (ANOVA). P values below .05 were considered significant. The strength of agreement between each set of measurements for the diagnosis of OH was assessed using kappa statistics, interpreted as suggested by Brennan and Silman (14).


   Results
Top
 Abstract
 Methods
 Results
Discussion
 References
 
Characteristics of the Patients
Fifty-three elderly patients (10 men and 43 women aged 83.7 ± 9.5 years) were included in the study. Their characteristics are reported in Table 1 .


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  		Table 1. Characteristics of the 53 Elderly Patients Studied

 
Resting Supine BP
Resting supine systolic and diastolic BP, measured on the six occasions, are shown in Table 2 . Repeated-measures ANOVA, based on the values obtained on the same day, showed significant changes in both systolic and diastolic BP. Compared with 8–9 AM values, systolic BP at 10–11 AM and both systolic and diastolic BP at 1–2 PM were significantly lower. However, there were no significant differences in the systolic or diastolic BP values recorded at the same times on different days (Table 2 ).


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  		Table 2. Resting Supine Blood Pressure (BP) Measured on Six Occasions in the 53 Patients Using an Oscillometric Automatized Device

 
BP Response to Orthostatism
Changes in BP after 1 and 2 minutes of orthostatism are reported in Table 3 . Repeated-measures ANOVA, based on the values obtained on the same day, showed significant changes in the responses to orthostatism of both systolic and diastolic BP (p < .05). However, there were no significant differences in the orthostatic systolic or diastolic changes observed at the same time of day on separate days.


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  		Table 3. Changes in Systolic and Diastolic Blood Pressure (BP, Supine Minus Standing) After 1 and 2 Minutes of Orthostatism

 
Reproducibility of the Diagnosis of OH
OH was defined as an OCs of 20 mm Hg or more. The number of patients who met this criterion at 1 minute of orthostatism varied from two to seven (4%–13%; Table 4 ), depending on the time of the reading. The corresponding OCs values at 2 minutes of orthostatism also displayed large variations (Table 4 ).


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  		Table 4. Patients With Orthostatic Hypotension (OH) Defined as a Decline in Systolic Blood Pressure of 20 mm Hg or More After 1 or 2 Minutes of Orthostatism

 
The number of cumulative cases (i.e., the number of patients with OCs of 20 mm Hg or more on at least one occasion) increased from seven (13%) for the initial set of measures to 21 (40%) for the last set, as indicated by the OCs values at 1 minute of orthostatism (Table 4 ). On the basis of the largest OCs after 1 and 2 minutes, the number of cumulative cases increased from ten (10%) for the initial set of measures to 23 (43%) for the last ones (Table 4 ). When OCs values at 1 minute were considered, the strength of agreement for the diagnosis of OH between the four sets of measurements done on the first day was poor to moderate (kappa values ranged from 0.12 to 0.47; Table 5 ). When the largest of the 1- and 2-minute OCs values was considered, this agreement was only a little better (kappa values from 0.23 to 0.54). The strength of agreement between the measurements recorded on different days at the same times was poor to fair (kappa values from 0.17 to 0.32; Table 6 ).


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  		Table 5. Agreement Between the Six Sets of Measurements for the Diagnosis of Orthostatic Hypotension*

 

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  		Table 6. Agreement Between the Six Sets of Measurements for the Diagnosis of Orthostatic Hypotension*

 

   Discussion
Top
 Abstract
 Methods
 Results
 Discussion
References
 
This study showed that the response of systolic BP to orthostatism exhibits significant within-day variations in elderly hospital patients who were in stable medical condition. In addition, the diagnosis of OH, defined as an OCs of 20 mm Hg or more at 1 or 2 minutes of orthostatism was variable, depending on whether it was based on different sets of measurements recorded on the same day or on 2 different days. This indicated that the reproducibility of the diagnosis was poor. The addition of criteria for OH, based on orthostatic changes in diastolic BP, did not improve the reproducibility of the diagnosis. These results, obtained in a population at risk for OH, might have practical implications for the diagnosis of this condition.

The differences between the OCs observed at different times during the same day were significant and in agreement with the results of other studies (12)(13)(15). In our study, these differences cannot have been due to the method of BP measurement, because we used a validated automatized oscillometric device to avoid inter- and intraobserver variability. However, the way in which patients moved off their beds to stand up varied from one series of measurements to another, especially among the very old frail subjects, and this may have caused variability in the time required to stand up and/or in the muscular and venous changes involved during active orthostatism. Another factor that may have caused OCs variability might be drug therapy, as suggested by Janssen (9). In our study, many patients were taking cardiovascular drugs, which might have modified BP regulation. However, at the time of the study, all patients were in a stable medical condition, with no recent change in their drug regimen, so that their treatments can be considered to have been in a steady-state phase. Further, the mean OCs was greatest at 8–9 AM, whereas drug concentrations and effects were usually smallest at that time, because no medication was given before the BPRO test. This suggested that overall chronic drug treatments probably did not have a major effect on OCs variability in our study. This view is supported by the earlier finding that no chronic drug treatment was clearly found to be a significant determinant of the BPRO in frail elderly people similar to our patients (13). Great OCs variability might also result from the aging process. Variability in resting BP was, in fact, shown to increase with advancing age caused by alterations in the mechanisms responsible for BP control (16). Cardiovascular autonomic responses are blunted by aging (17), which reduces resting heart rate variability, but increases BP variability (18)(19)(20). Baroreflex control is also less efficient in elderly subjects (21). It is therefore likely that these alterations in BP control might affect not only resting BP, but also BP changes during orthostatism. Consequently, less efficient BP control might also be responsible for larger variability in the BP response to orthostatism.

Since postprandial hypotension was reported to be very common in elderly institutionalized patients (22), one might expect alterations in BP control to be especially marked after meals. However, we did not find particularly large OCs under postprandial conditions, and especially not at 1–2 PM, even if resting BP was significantly reduced at that time compared with 8–9 AM values. Mealtimes and BP measurement times were not rigidly fixed in our study, unlike the studies especially designed for postprandial hypotension research, but our findings are in agreement with those obtained in a large population of nursing home patients (13). In addition, the mechanisms involved in postprandial hypotension are probably very different from those governing the BP response to orthostatism (9)(22)(23)(24).

Whatever the mechanisms involved in the variability of this response, our results might have important implications for the diagnosis of OH in elderly persons. These results clearly indicate that when this diagnosis is based on the conventional criteria, it is poorly reproducible. When we based it on a decline in systolic and/or diastolic BP after 1 or 2 minutes of orthostatism, its reproducibility did not improve.

Our conclusion is in agreement with that of Ward and Kenny (12), who showed that only 33% of elderly patients with symptomatic documented OH had OCs of 20 mm Hg or more when a second set of measures was done on the same morning. A similar conclusion was obtained by Alli and coworkers, who found in a large sample of elderly subjects that only 36% of those with OH defined as OCs of 20 mm Hg or more still met the same criterion on a second visit 7 days later (25). The poor reproducibility of the diagnosis of OH might be of practical importance in symptomatic patients, when initial screening for OH is negative. Because patients who experience a decrease in systolic BP on a single occasion might be exposed to the risk of dizziness, falls, and complications, we believe that clinicians could assess the BP response to orthostatism several times on the same day, before excluding the diagnosis of OH. Detection of drug-induced OH might also be a serious problem in asymptomatic patients taking drugs that alter cardiovascular regulation.

Finally, we suggest that conventional criteria for the diagnosis of OH in elderly persons should be revised by appropriate methodological approaches. In our view, there is a need for prospective studies designed to determine new criteria capable of identifying elderly patients at risk of experiencing dizziness or falls as a result of their BP response to standing. The reproducibility of these criteria, as well as their sensitivity and specificity for the diagnosis, also should be carefully assessed. The availability of effective treatment of OH in elderly persons, as demonstrated by a recent randomized controlled trial (26), is a strong argument for establishing effective methods of diagnosing this condition.

Received September 3, 1999

Accepted February 2, 2000


   References
Top
 Abstract
 Methods
 Results
 Discussion
 References
 

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