Diagnostic precision of mentally estimated home blood pressure means.

CONTEXT: Paper home blood pressure (HBP) charts are commonly brought to physicians at office visits. The precision and accuracy of mental calculations of blood pressure (BP) means are not known. METHODS: A total of 109 hypertensive patients were instructed to measure and record their HBP for 1 week and to bring their paper charts to their office visit. Study section 1: HBP means were calculated electronically and compared to corresponding in-office BP estimates made by physicians. Study section 2: 100 randomly ordered HBP charts were re-examined repetitively by 11 evaluators. Each evaluator estimated BP means four times in 5, 15, 30, and 60 s (random order) allocated for the task. BP means and diagnostic performance (determination of therapeutic systolic and diastolic BP goals attained or not) were compared between physician estimates and electronically calculated results. RESULTS: Overall, electronically and mentally calculated BP means were not different. Individual analysis showed that 83% of in-office physician estimates were within a 5-mmHg systolic BP range. There was diagnostic disagreement in 15% of cases. Performance improved consistently when the time allocated for BP estimation was increased from 5 to 15 s and from 15 to 30 s, but not when it exceeded 30 s. CONCLUSION: Mentally calculating HBP means from paper charts can cause a number of diagnostic errors. Chart evaluation exceeding 30 s does not significantly improve accuracy. BP-measuring devices with modern analytical capacities could be useful to physicians.

Comparison of Different Automated Office Blood Pressure Measurement Devices: Evidence of Nonequivalence and Clinical Implications.

BACKGROUND: Automated office blood pressure (AOBP) measuring devices are increasingly recommended as preferred blood pressure (BP) diagnostic tools, but it is unclear how they compare and how clinical environments impact their performance. METHODS: This prospective randomized factorial parallel 4-group study compared BP estimates by BpTRU (VSM MedTech, Vancouver, BC, Canada) and Omron HEM 907 (Omron Healthcare, Kyoto, Japan) devices in closed vs open areas. Patients diagnosed with hypertension were recruited during office visits. After baseline open-room AOBP measurement with the BpTRU, patients had a second BP measurement with either the BpTRU or HEM 907 in either open or closed areas. Absolute BP levels and differences between the first and second measurements were compared. Diagnostic performance was also assessed. RESULTS: Two hundred fifty-eight patients were studied. Their mean age was 66.2 ± 12.0 years, and 62% were men. The mean of first AOBP estimates was 127.4/73.3 mm Hg. Analyses of subsequent measurements revealed no influence of open or closed areas on BP means and diagnostic performance. Conversely, the Omron HEM 907 exceeded BpTRU systolic BP measurements by 4.6 mm Hg (< 0.01) in closed areas and by 3.9 mm Hg (< 0.01) in open areas. The discrepancy between devices was amplified at lower BP levels. CONCLUSIONS: Although different areas did not influence BP estimates, the Omron HEM 907 significantly exceeded BpTRU measurements on average and especially at lower BP levels. These differences should be considered when interchanging devices and could have clinical decision impacts in a population of patients treated for hypertension. Our results support the constant use of only 1 device type in a given clinic.

The Gap Between Manual and Automated Office Blood Pressure Measurements Results at a Hypertension Clinic.

BACKGROUND: Blood pressure (BP) readings taken in clinics are often higher than BP readings taken in a research setting. Recent guidelines and clinical trials have highlighted the necessity of using automated office blood pressure (AOBP) devices and standardizing measurement procedures. The goal of the present study was to compare AOBP vs manual BP measurement in both research and clinical environments in which operators and devices were the same and measurement procedures were standardized and optimal. METHODS: Clinical manual BP and AOBP measurement estimates were gathered from a retrospective cohort of patients followed in a hypertension clinic. Research AOBP and manual BP measurement data were obtained from past research studies. Descriptive statistics and agreement analyses with Cohen kappa coefficients were developed. The AOBP/manual BP measurement gap between clinical and research follow-up was compared using an unpaired t test. RESULTS: Two hundred eighty-eight patients were included in the clinical cohort, and 195 patients contributed to research-grade BP data. All patients had hypertension. AOBP averages were lower than manual measurement averages in both clinical (-3.6 ± 14.9 mm Hg / -3.0 ± 8.8 mm Hg) and research (-2.7 ± 10.0 / -2.4 ± 6.3 mm Hg) environments. The gap between measurement methods did not differ between research and clinical data. Cohen kappa coefficient was lower in the clinical context because of greater variability and more time between BP measurements (5.5 ± 2.9 months). CONCLUSIONS: Manual BP readings were slightly higher than AOBP estimates. The difference was not influenced by the real-world context of clinical practice. Office nonautomated BP measurements may still be valuable if measurement procedures are well standardized and performed by trained nurses.

Quantification of the External Validity of Randomized Controlled Trials Supporting Clinical Care Guidelines: The Case of Thromboprophylaxis.

BACKGROUND: Clinical guidelines are based on the results of several randomized controlled trials. However, due to the stringent exclusion criteria of these trials, their external validity may be low. We aimed to evaluate the external validity of the randomized controlled trials cited in the American College of Chest Physicians guidelines for the use of pharmacological thromboprophylaxis in hospitalized medical patients. METHODS: We conducted a cross-sectional, chart-review study of a random sample of patients admitted between July 1, 2013 and June 30, 2014 to the Internal Medicine ward of a large Canadian teaching university hospital. We identified the proportion of our population presenting exclusion criteria used in the randomized controlled trials cited in support of clinical care guidelines on thromboprophylaxis in the medical setting. RESULTS: Nine trials were identified for a total of 28,793 included patients following 23 distinct exclusion criteria. We included 429 patients. Median age was 65 years (interquartile ratio 51-77 years), and 236 (55%) were males. Of those not already anticoagulated at admission (n = 351), between 26% and 67% (weighted average, 51%) of our population presented at least one exclusion criterion, making them ineligible to be enrolled in randomized controlled trials. When restricting our population to patients with an indication for thromboprophylaxis based on a Padua risk score at admission ≥4, 21% to 76% (weighted average 55%) were ineligible to be enrolled in individual trials. CONCLUSIONS: Our cross-sectional study illustrates that the external validity of randomized controlled trials cited in the guidelines was low in our population, and lower when applying the risk-stratification tool recommended by guidelines. This can bias the clinicians toward treating patients that were not represented in the supporting evidence.

Unreliability of home blood pressure measurement and the effect of a patient-oriented intervention.

BACKGROUND: Home blood pressure (BP) measurement (HBPM) is recommended for the diagnosis and follow-up of high BP. It is unclear how this aspect of BP monitoring has evolved over the years and whether interventions could influence patient adherence to HBPM guidelines. METHODS: After a questionnaire-based cross-sectional study performed in 2010, a passive, multimodal intervention, focused on improving adherence to HBPM guidelines, was implemented. A second study was conducted in 2014 to measure its effect. RESULTS: In 2010 and 2014, 1010 and 1005 patients, respectively, completed the questionnaire. In 2010 and 2014, 82% and 84% of patients, respectively, self-measured their BP. Reporting of HBPM and adherence to recommended procedures was suboptimal. Only 34.0% of patients in 2010 and 31.7% in 2014 brought > 80% of their measurements to their doctor. Only 49.6% in 2010 and 52.9% in 2014 prepared > 80% of the time for HBPM. Only 48.1% in 2010 and 52.1% in 2014 rested for 5 minutes > 80% of the time before HBPM. Only 15% of patients in 2010 and 18% in 2014 were defined as sufficiently compliant with all HBPM procedures. Paired analysis of a subset of 535 patients who participated in the 2010 and 2014 studies showed no clinically significant differences in reliability between the 2 surveys. CONCLUSIONS: Adherence to HBPM guidelines was suboptimal in 2010 and still is in 2014 despite a passive, multimodal intervention. Active training in HBPM procedures should be studied. Greater automation could improve HBPM reliability.

Lack of Clinical Benefit of Thromboprophylaxis in Patients Hospitalized in a Medical Unit Over a 10-year Span.

BACKGROUND: Thromboprophylaxis for hospitalized patients with a high risk of venous thromboembolic events (VTEs) is strongly recommended but is not universally applied on medical units. Outside of randomized trials, there is minimal evidence that the usual medications reduce the incidence of clinically significant VTE. METHODS: We conducted a retrospective cohort study including all patients admitted into a teaching medical unit during years 2001-2002, 2003-2004, 2005-2006, 2007-2008 and 2009-2010. Inclusion criteria for the analysis were having one or more risk factors for a VTE and no contraindication to thromboprophylaxis. RESULTS: Of 2,369 patients reviewed, 1,302 satisfied the inclusion criteria. Between years 2001-2002 and 2009-2010, the proportion of patients receiving thromboprophylaxis increased from 29.2% to 76.4% (P < 0.0001) and the duration of thromboprophylaxis increased from 63% of hospital stay to 84% (P = 0.004). There was no statistically significant association between the number of risk factors and the rate of thromboprophylaxis. Overall, only 32 patients suffered from a VTE with no decrease in VTE incidence between years 2001-2002 and 2009-2010. A total of 107 patients had a bleeding event, and there was no statistically significant change in the incidence of bleeding during our study period. CONCLUSIONS: In our medical units, we found a statistically significant increase in the use of the thromboprophylaxis practice. However, this was not associated with any statistically significant impact on the VTE incidence. This suggests that patients given thromboprophylaxis could be better selected.

Influence of thrombophilia on risk of recurrent venous thromboembolism while on warfarin: results from a randomized trial.

We sought to determine whether thrombophilic defects increase recurrent venous thromboembolism (VTE) during warfarin therapy. Six hundred sixty-one patients with unprovoked VTE who were randomized to extended low-intensity (international normalized ratio [INR], 1.5-1.9) or conventional-intensity (INR, 2.0-3.0) anticoagulant therapy were tested for thrombophilia and followed for a mean of 2.3 years. One or more thrombophilic defects were present in 42% of patients. The overall rate of recurrent VTE was 0.9% per patient-year. Recurrent VTE was not increased in the presence of factor V Leiden (hazard ratio [HR], 0.7; 95% CI, 0.2-2.6); the 20210G>A prothrombin gene mutation (HR, 0); antithrombin deficiency (HR, 0); elevated factor VIII (HR, 0.7; 95% CI, 0.1-5.4); elevated factor XI (HR, 0.7; 95% CI, 0.1-5.0), or elevated homocysteine (HR, 0.7; 95% CI, 0.1-5.3), but showed a trend to an increase with an antiphospholipid antibody (HR, 2.9; 95% CI, 0.8-10.5). Compared with patients with no thrombophilic defects, the rate of recurrence was not increased in the presence of one (HR, 0.7; 95% CI, 0.2-2.3) or more than one (HR, 0.7; 95% CI, 0.2-3.4) defect. We conclude that single or multiple thrombophilic defects are not associated with a higher risk of recurrent VTE during warfarin therapy.

Comparison of low-intensity warfarin therapy with conventional-intensity warfarin therapy for long-term prevention of recurrent venous thromboembolism.

BACKGROUND: Warfarin is very effective in preventing recurrent venous thromboembolism but is also associated with a substantial risk of bleeding. After three months of conventional warfarin therapy, a lower dose of anticoagulant medication may result in less bleeding and still prevent recurrent venous thromboembolism. METHODS: We conducted a randomized, double-blind study, in which 738 patients who had completed three or more months of warfarin therapy for unprovoked venous thromboembolism were randomly assigned to continue warfarin therapy with a target international normalized ratio (INR) of 2.0 to 3.0 (conventional intensity) or a target INR of 1.5 to 1.9 (low intensity). Patients were followed for an average of 2.4 years. RESULTS: Of 369 patients assigned to low-intensity therapy, 16 had recurrent venous thromboembolism (1.9 per 100 person-years), as compared with 6 of 369 assigned to conventional-intensity therapy (0.7 per 100 person-years; hazard ratio, 2.8; 95 percent confidence interval, 1.1 to 7.0). A major bleeding episode occurred in nine patients assigned to low-intensity therapy (1.1 events per 100 person-years) and eight patients assigned to conventional-intensity therapy (0.9 event per 100 person-years; hazard ratio, 1.2; 95 percent confidence interval, 0.4 to 3.0). There was no significant difference in the frequency of overall bleeding between the two groups (hazard ratio, 1.3; 95 percent confidence interval, 0.8 to 2.1). CONCLUSIONS: Conventional-intensity warfarin therapy is more effective than low-intensity warfarin therapy for the long-term prevention of recurrent venous thromboembolism. The low-intensity warfarin regimen does not reduce the risk of clinically important bleeding.