Randomised equivalence trial comparing three month and six month follow up of patients with hypertension by family practitioners
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《英国医生杂志》
1 Centre for Studies in Primary Care, Queen's University, PO Bag 8888, Kingston, ON, Canada K7L 5E9, 2 Department of Community Health and Epidemiology, Queen's University, Kingston, ON, Canada K7L 3N6
Correspondence to: R Birtwhistle birtwhis@post.queensu.ca
Abstract
One of the achievements of contemporary health care is the decrease in morbidity and mortality through the control of chronic cardiovascular conditions such as hypertension. The mortality from cardiovascular disease has fallen by a third over the past 25 years, and although the reasons for this have not been clearly established, control of hypertension may be a central reason.1 However, control of blood pressure by patients and their doctors is still far from ideal. The Canada heart health survey found that only about 13% of Canadians with hypertension were adequately controlled.2 This result was even lower than the 25% found in the US National Health and Nutrition Examination Survey (NHANES III).3 After initial diagnosis and treatment of chronic diseases such as hypertension, most people need lifelong medical care and follow up, and their doctors must decide how often to follow up for blood pressure control and monitoring of treatment.
Currently, the suggested intervals for follow up of hypertension come from consensus guidelines. The National Committee on Detection, Evaluation and Treatment of High Blood pressure (JNC7) recommends that once the blood pressure is stabilised, follow up every 3-6 months is appropriate.4 The British Hypertension Society says that follow up depends on the severity of hypertension, variability of blood pressure, complexity of treatment regimen, patient's compliance with treatment, and the need for non-pharmacological advice. After blood pressure is controlled, follow up every three months should be adequate and the interval should generally not exceed six months.5 The 1999 Canadian consensus guidelines recommend similar intervals.6 All of these recommendations are based on level 3 evidence. Several studies have assessed doctors' practices of treating patients with hypertension. Some saw patients every two weeks, some once a year.7-10 As McDonald has suggested, perhaps the three and six month follow up intervals are based on phases of the moon because nothing better exists.11
The hypertension follow up interval study began in November 1997 and ended in July 2002. It is a randomised equivalence trial comparing three month and six month follow up of patients whose essential hypertension had been treated and controlled for at least three months before entry into the study. This was designed as a pragmatic trial of the follow up of people with hypertension. Decisions about treatment after the initial randomisation were left to the family doctor and the patient. The study was designed to determine whether blood pressure control, adherence to treatment, and patient satisfaction were equivalent between the groups after three years of follow up. We also assessed cost of care, which will be addressed elsewhere. The figure shows the flow of patients through the trial.
Flow of patients through the hypertension follow up interval study. Patients were followed by chart review and included in the analysis unless they moved or died
Methods
Six hundred and nine patients (302 in the three month group and 307 in the six month group) were enrolled by 50 family doctors and followed over an average of 33.6 months. With the predefined equivalence margins and the standard errors of the differences between groups, the power for identifying group equivalence (if the groups are truly identical) was over 89% for all the comparisons of blood pressure. For patient satisfaction, most of the scores had over 70% power, but for two (length of consultation and depth of relationship) the data showed more variation with larger standard error.
Baseline variables were similar in the groups (table 1). However, the three month group contained more patients with diabetes.
Table 1 Comparison of baseline variables at entry between groups. Values are numbers (percentages) of patients unless indicated otherwise
Table 2 shows that a total of 10 659 visits were made during the study. The six month group had more unscheduled visits for measuring blood pressure and more visits unrelated to blood pressure, although the difference between groups was not significant (8.68 v 7.95, P = 0.23). The six month group had significantly fewer visits to the doctor over the three years (mean 16.2 (SD 8.5) visits in six month group v 18.8 (8.1) in three month group, P < 0.0001). The mean time between visits was 2.16 (2.25) months for the six month group and 1.89 (1.61) months for the three month group.
Table 2 Number of visits to doctor over three years
Control of hypertension
At 0, 12, 24, and 36 months mean blood pressure measured by doctors during a consultation were equivalent between groups (table 3). The mean blood pressure measurements taken at patients' homes by nurses were similar to the doctors' measurements but were consistently lower in years 2 and 3 (table 4). There was a trend to lower blood pressure readings in both groups after three years for both the doctors' and nurses' measurements.
Table 3 Mean (SE) numbers of systolic and diastolic blood pressure measurements (mm Hg) in patients with hypertension by family doctors
Table 4 Mean (SE) systolic and diastolic blood pressure (mm Hg) measured by nurses
Table 5 shows the percentage of patients whose blood pressure was out of control as judged by their doctor over the course of the study. Although we provided doctors with guidelines for levels of blood pressure that should be considered out of control, we asked them to use their own judgment.
Table 5 Number (percentage) of patients whose blood pressure was out of control as judged by doctor
Satisfaction with medical care
All of the factors measured for patient satisfaction were equivalent in the two groups (table 6), as was patients' satisfaction with the care of their blood pressure by their doctor (table 7). More patients in the six month group thought that the doctor did not take their blood pressure problem seriously enough towards the end of the study.
Table 6 Patients' satisfaction with their care. Values are numbers (percentages) unless otherwise indicated
Table 7 Patients' satisfaction with their doctor's care of their hypertension. Values are numbers (percentages) unless otherwise indicated
Adherence to treatment
Adherence to treatment was equivalent between groups. However, we found that pill counts in this pragmatic trial were unreliable. The research nurse found it difficult to determine exactly how many pills some patients who were taking multiple drugs had taken. Table 8 shows results from the compliance questionnaire.12 At entry, more patients in the three month group forgot to take their blood pressure drug. Otherwise, the groups were equivalent.
Table 8 Adherence to treatment by hypertensive patients. Values are numbers (percentages) of patients unless specified otherwise
Self monitoring of blood pressure
Sixty per cent of patients in the three month group and 57% in the six month group measured their blood pressure outside of the office setting (home, work, pharmacy). At entry, 36% of patients in the three month group and 39% of the six month group measured their blood pressure at home. By the end of the study, this increased to 52% (three month group) and 47% (six month group).
Discussion
Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Sixth report. Bethesda: National Institutes of Health, 1997. (NIH publication No 98-4080.)
Joffres MR, Hamet P, MacLean DR, L'italien GL, Fodor G. Distribution of blood pressure and hypertension in Canada and the United States. AJH 2001;14: 1099 -105.
Burt VL, Cutler JA, Higgins M, Horan MJ, Labarthe D, Whelton P, et al. Trends in the prevalence, awareness, treatment, and control of hypertension in the adult US population. Data from the health examination surveys, 1960 to 1991. Hypertension 1995;26: 60 -9.
Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LE, Izzo JL, et al. The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. JAMA 2003;289: 2560 -72.
Ramsay LE, Williams B, Johnston GD, MacGregor GA, Poston L, Potter JF, et al for the British Hypertension Society. Guidelines for management of hypertension: report of the third working party of the British Hypertension Society. J Hum Hypertensn 1999;13: 569 -92.
Canadian Hypertension Recommendations Working Group. The 2001 Canadian hypertension recommendations. What is new and what is old but still important. Can J Cardiol 2002;18: 591 -603.
Petitti DB, Grumbach K. Variation in physicians' recommendations about revisit interval for three common conditions. J Fam Pract 1993;37: 235 -40.
Lichenstein MJ, Sweetnam PM, Elwood PC. Visit frequency for controlled essential hypertension: general practitioners' opinions. J Fam Pract 1986;23: 331 -6.
Tobacman JK, Zeitler RR, Cilursu AM, Mori M. Variation in physician opinion about scheduling of return visits for common ambulatory care conditions. J Gen Intern Med 1992;7: 312 -6.
Lichenstein MJ, Steele MA, Hoehn TP, Bulpitt CJ, Coles EC. Visit frequency for essential hypertension. J. Fam Pract 1989;28: 667 -72.
McDonald CJ. Medical heuristics: the silent adjudicators of clinical practice. Ann Intern Med 1996;124: 56 -62.
Frohlich ED. Blood pressure measurement. Can J Cardiol 1995;11(suppl): 35 -7H.
Baker R. Development of a questionnaire to assess patients' satisfaction with consultations in general practice. Br J Gen Pract 1990;40: 487 -90.
Baker R. Dialogue 3rd edition, a method for surveying patient satisfaction. Leicester: Clinical Governance Research and Development Unit, Department of General Practice and Primary Health Care, University of Leicester, 2001.
Gregoire JP, Archambault A, Contrandriopoulos AP, Guilbert R. Medication compliance in a family practice. Can Fam Physician 1992;38: 2333 -7.
Dunnet CW, Gent M. Significance testing to establish equivalence between treatments, with special reference to data in the form of 2x2 tables. Biometrics 1977;33: 593 -602.
Hsu JC, Hwang JT, Liu HK, Ruberg SJ. Confidence intervals associated with tests for bioequivalence. Biometrika 1994;81: 103 -14.
Diggle PJ, Liang KY, Zegler SL. The analysis of longitudinal data. New York: Oxford University Press, 1994.
Agresti A. Categorical data analysis. New York: Wiley, 1990: 419.
Phillips LS, Branch WT, Cook CB, Doyle JP, El-Kebbi IM, Gallina DL et al. Clinical inertia. Ann Intern Med 2001;135: 825 -34.(Richard V Birtwhistle, pr)
Correspondence to: R Birtwhistle birtwhis@post.queensu.ca
Abstract
One of the achievements of contemporary health care is the decrease in morbidity and mortality through the control of chronic cardiovascular conditions such as hypertension. The mortality from cardiovascular disease has fallen by a third over the past 25 years, and although the reasons for this have not been clearly established, control of hypertension may be a central reason.1 However, control of blood pressure by patients and their doctors is still far from ideal. The Canada heart health survey found that only about 13% of Canadians with hypertension were adequately controlled.2 This result was even lower than the 25% found in the US National Health and Nutrition Examination Survey (NHANES III).3 After initial diagnosis and treatment of chronic diseases such as hypertension, most people need lifelong medical care and follow up, and their doctors must decide how often to follow up for blood pressure control and monitoring of treatment.
Currently, the suggested intervals for follow up of hypertension come from consensus guidelines. The National Committee on Detection, Evaluation and Treatment of High Blood pressure (JNC7) recommends that once the blood pressure is stabilised, follow up every 3-6 months is appropriate.4 The British Hypertension Society says that follow up depends on the severity of hypertension, variability of blood pressure, complexity of treatment regimen, patient's compliance with treatment, and the need for non-pharmacological advice. After blood pressure is controlled, follow up every three months should be adequate and the interval should generally not exceed six months.5 The 1999 Canadian consensus guidelines recommend similar intervals.6 All of these recommendations are based on level 3 evidence. Several studies have assessed doctors' practices of treating patients with hypertension. Some saw patients every two weeks, some once a year.7-10 As McDonald has suggested, perhaps the three and six month follow up intervals are based on phases of the moon because nothing better exists.11
The hypertension follow up interval study began in November 1997 and ended in July 2002. It is a randomised equivalence trial comparing three month and six month follow up of patients whose essential hypertension had been treated and controlled for at least three months before entry into the study. This was designed as a pragmatic trial of the follow up of people with hypertension. Decisions about treatment after the initial randomisation were left to the family doctor and the patient. The study was designed to determine whether blood pressure control, adherence to treatment, and patient satisfaction were equivalent between the groups after three years of follow up. We also assessed cost of care, which will be addressed elsewhere. The figure shows the flow of patients through the trial.
Flow of patients through the hypertension follow up interval study. Patients were followed by chart review and included in the analysis unless they moved or died
Methods
Six hundred and nine patients (302 in the three month group and 307 in the six month group) were enrolled by 50 family doctors and followed over an average of 33.6 months. With the predefined equivalence margins and the standard errors of the differences between groups, the power for identifying group equivalence (if the groups are truly identical) was over 89% for all the comparisons of blood pressure. For patient satisfaction, most of the scores had over 70% power, but for two (length of consultation and depth of relationship) the data showed more variation with larger standard error.
Baseline variables were similar in the groups (table 1). However, the three month group contained more patients with diabetes.
Table 1 Comparison of baseline variables at entry between groups. Values are numbers (percentages) of patients unless indicated otherwise
Table 2 shows that a total of 10 659 visits were made during the study. The six month group had more unscheduled visits for measuring blood pressure and more visits unrelated to blood pressure, although the difference between groups was not significant (8.68 v 7.95, P = 0.23). The six month group had significantly fewer visits to the doctor over the three years (mean 16.2 (SD 8.5) visits in six month group v 18.8 (8.1) in three month group, P < 0.0001). The mean time between visits was 2.16 (2.25) months for the six month group and 1.89 (1.61) months for the three month group.
Table 2 Number of visits to doctor over three years
Control of hypertension
At 0, 12, 24, and 36 months mean blood pressure measured by doctors during a consultation were equivalent between groups (table 3). The mean blood pressure measurements taken at patients' homes by nurses were similar to the doctors' measurements but were consistently lower in years 2 and 3 (table 4). There was a trend to lower blood pressure readings in both groups after three years for both the doctors' and nurses' measurements.
Table 3 Mean (SE) numbers of systolic and diastolic blood pressure measurements (mm Hg) in patients with hypertension by family doctors
Table 4 Mean (SE) systolic and diastolic blood pressure (mm Hg) measured by nurses
Table 5 shows the percentage of patients whose blood pressure was out of control as judged by their doctor over the course of the study. Although we provided doctors with guidelines for levels of blood pressure that should be considered out of control, we asked them to use their own judgment.
Table 5 Number (percentage) of patients whose blood pressure was out of control as judged by doctor
Satisfaction with medical care
All of the factors measured for patient satisfaction were equivalent in the two groups (table 6), as was patients' satisfaction with the care of their blood pressure by their doctor (table 7). More patients in the six month group thought that the doctor did not take their blood pressure problem seriously enough towards the end of the study.
Table 6 Patients' satisfaction with their care. Values are numbers (percentages) unless otherwise indicated
Table 7 Patients' satisfaction with their doctor's care of their hypertension. Values are numbers (percentages) unless otherwise indicated
Adherence to treatment
Adherence to treatment was equivalent between groups. However, we found that pill counts in this pragmatic trial were unreliable. The research nurse found it difficult to determine exactly how many pills some patients who were taking multiple drugs had taken. Table 8 shows results from the compliance questionnaire.12 At entry, more patients in the three month group forgot to take their blood pressure drug. Otherwise, the groups were equivalent.
Table 8 Adherence to treatment by hypertensive patients. Values are numbers (percentages) of patients unless specified otherwise
Self monitoring of blood pressure
Sixty per cent of patients in the three month group and 57% in the six month group measured their blood pressure outside of the office setting (home, work, pharmacy). At entry, 36% of patients in the three month group and 39% of the six month group measured their blood pressure at home. By the end of the study, this increased to 52% (three month group) and 47% (six month group).
Discussion
Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Sixth report. Bethesda: National Institutes of Health, 1997. (NIH publication No 98-4080.)
Joffres MR, Hamet P, MacLean DR, L'italien GL, Fodor G. Distribution of blood pressure and hypertension in Canada and the United States. AJH 2001;14: 1099 -105.
Burt VL, Cutler JA, Higgins M, Horan MJ, Labarthe D, Whelton P, et al. Trends in the prevalence, awareness, treatment, and control of hypertension in the adult US population. Data from the health examination surveys, 1960 to 1991. Hypertension 1995;26: 60 -9.
Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LE, Izzo JL, et al. The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. JAMA 2003;289: 2560 -72.
Ramsay LE, Williams B, Johnston GD, MacGregor GA, Poston L, Potter JF, et al for the British Hypertension Society. Guidelines for management of hypertension: report of the third working party of the British Hypertension Society. J Hum Hypertensn 1999;13: 569 -92.
Canadian Hypertension Recommendations Working Group. The 2001 Canadian hypertension recommendations. What is new and what is old but still important. Can J Cardiol 2002;18: 591 -603.
Petitti DB, Grumbach K. Variation in physicians' recommendations about revisit interval for three common conditions. J Fam Pract 1993;37: 235 -40.
Lichenstein MJ, Sweetnam PM, Elwood PC. Visit frequency for controlled essential hypertension: general practitioners' opinions. J Fam Pract 1986;23: 331 -6.
Tobacman JK, Zeitler RR, Cilursu AM, Mori M. Variation in physician opinion about scheduling of return visits for common ambulatory care conditions. J Gen Intern Med 1992;7: 312 -6.
Lichenstein MJ, Steele MA, Hoehn TP, Bulpitt CJ, Coles EC. Visit frequency for essential hypertension. J. Fam Pract 1989;28: 667 -72.
McDonald CJ. Medical heuristics: the silent adjudicators of clinical practice. Ann Intern Med 1996;124: 56 -62.
Frohlich ED. Blood pressure measurement. Can J Cardiol 1995;11(suppl): 35 -7H.
Baker R. Development of a questionnaire to assess patients' satisfaction with consultations in general practice. Br J Gen Pract 1990;40: 487 -90.
Baker R. Dialogue 3rd edition, a method for surveying patient satisfaction. Leicester: Clinical Governance Research and Development Unit, Department of General Practice and Primary Health Care, University of Leicester, 2001.
Gregoire JP, Archambault A, Contrandriopoulos AP, Guilbert R. Medication compliance in a family practice. Can Fam Physician 1992;38: 2333 -7.
Dunnet CW, Gent M. Significance testing to establish equivalence between treatments, with special reference to data in the form of 2x2 tables. Biometrics 1977;33: 593 -602.
Hsu JC, Hwang JT, Liu HK, Ruberg SJ. Confidence intervals associated with tests for bioequivalence. Biometrika 1994;81: 103 -14.
Diggle PJ, Liang KY, Zegler SL. The analysis of longitudinal data. New York: Oxford University Press, 1994.
Agresti A. Categorical data analysis. New York: Wiley, 1990: 419.
Phillips LS, Branch WT, Cook CB, Doyle JP, El-Kebbi IM, Gallina DL et al. Clinical inertia. Ann Intern Med 2001;135: 825 -34.(Richard V Birtwhistle, pr)