Investigation of end-digit preference in blood pressure records of hospitalized chinese patients and analysis of risk factors

Are self-reported telemonitored blood pressure readings affected by end-digit preference: a prospective cohort study in Scotland

OBJECTIVE

Simple forms of blood pressure (BP) telemonitoring require patients to text readings to central servers creating an opportunity for both entry error and manipulation. We wished to determine if there was an apparent preference for particular end digits and entries which were just below target BPs which might suggest evidence of data manipulation.

DESIGN

Prospective cohort study SETTING: 37 socioeconomically diverse primary care practices from South East Scotland.

PARTICIPANTS

Patients were recruited with hypertension to a telemonitoring service in which patients submitted home BP readings by manually transcribing the measurements into text messages for transmission ('patient-texted system'). These readings were compared with those from primary care patients with uncontrolled hypertension using a system in which readings were automatically transmitted, eliminating the possibility of manipulation of values ('automatic-transmission system').

METHODS

A generalised estimating equations method was used to compare BP readings between the patient-texted and automatic-transmission systems, while taking into account clustering of readings within patients.

RESULTS

A total of 44 150 BP readings were analysed on 1068 patients using the patient-texted system compared with 20 705 readings on 199 patients using the automatic-transmission system. Compared with the automatic-transmission data, the patient-texted data showed a significantly higher proportion of occurrences of both systolic and diastolic BP having a zero end digit (OR 2.1, 95% CI 1.7 to 2.6) although incidence was <2% of readings. Similarly, there was a preference for systolic 134 and diastolic 84 (the threshold for alerts was 135/85) (134 systolic BP OR 1.5, 95% CI 1.3 to 1.8; 84 diastolic BP OR 1.5, 95% CI 1.3 to 1.9).

CONCLUSION

End-digit preference for zero numbers and specific-value preference for readings just below the alert threshold exist among patients in self-reporting their BP using telemonitoring. However, the proportion of readings affected is small and unlikely to be clinically important.

TRIAL REGISTRATION NUMBER

ISRCTN72614272; Post-results.

Sources of inaccuracy in the measurement of adult patients' resting blood pressure in clinical settings: a systematic review

BACKGROUND

To interpret blood pressure (BP) data appropriately, healthcare providers need to be knowledgeable of the factors that can potentially impact the accuracy of BP measurement and contribute to variability between measurements.

METHODS

A systematic review of studies quantifying BP measurement inaccuracy. Medline and CINAHL databases were searched for empirical articles and systematic reviews published up to June 2015. Empirical articles were included if they reported a study that was relevant to the measurement of adult patients' resting BP at the upper arm in a clinical setting (e.g. ward or office); identified a specific source of inaccuracy; and quantified its effect. Reference lists and reviews were searched for additional articles.

RESULTS

A total of 328 empirical studies were included. They investigated 29 potential sources of inaccuracy, categorized as relating to the patient, device, procedure or observer. Significant directional effects were found for 27; however, for some, the effects were inconsistent in direction. Compared with true resting BP, significant effects of individual sources ranged from -23.6 to +33 mmHg SBP and -14 to +23 mmHg DBP.

CONCLUSION

A single BP value outside the expected range should be interpreted with caution and not taken as a definitive indicator of clinical deterioration. Where a measurement is abnormally high or low, further measurements should be taken and averaged. Wherever possible, BP values should be recorded graphically within ranges. This may reduce the impact of sources of inaccuracy and reduce the scope for misinterpretations based on small, likely erroneous or misleading, changes.

Relations of body weight status in early adulthood and weight changes until middle age with hypertension in the Chinese population

We conducted a retrospective cohort study of adult participants from the China Multicenter Collaborative Study of Cardiovascular Epidemiology to explore the relationship between early adulthood weight status, body weight change from age 25 to middle age and hypertension in the Chinese population. Self-reported weight was used to calculate the body mass index (BMI) at age 25. The association between BMI at age 25, subsequent weight change and hypertension was examined using a logistic regression model. Of the 14 635 study participants sampled in 1998, 3525 were diagnosed with hypertension. After adjusting for age, sex and other potential confounding factors, both the BMI at age 25 and weight gain were positively associated with the risk of hypertension (P for trend <0.001). Weight loss could more effectively reduce the risk of hypertension for participants with a higher BMI (BMI⩾24 kg m^-2) at age 25 than for those who experienced a weight change of -2.5-2.5 kg. The odds ratio (OR) and 95% confidence interval (CI) for a weight change of -7.5 to -2.6 kg were 0.63 (0.46-0.86); for a weight change of <-7.5 kg, these statistics were 0.45 (0.32-0.63). For participants who had a lower BMI (18.5-20.9 kg m^-2) at age 25, the OR and 95% CI were 0.86 (0.58-1.26) for a weight change of -7.5 to -2.6 kg and 0.95 (0.44-2.05) for a weight change of <-7.5 kg. Being overweight and obesity in early adulthood and adult weight gain were both independently associated with marked increase in the risk of hypertension in middle-aged men and women. Weight loss may be a protective factor against hypertension for people who were overweight or obese in early adulthood.