Assessing the reliability of self-reported weight for the management of heart failure: application of fraud detection methods to a randomised trial of telemonitoring

Abstract

BackgroundSince clinical management of heart failure relies on weights that are self-reported by the patient, errors in reporting will negatively impact the ability of health care professionals to offer timely and effective preventive care. Errors might often result from rounding, or more generally from individual preferences for numbers ending in certain digits, such as 0 or 5. We apply fraud detection methods to assess preferences for numbers ending in these digits in order to inform medical decision making.MethodsThe Telemonitoring to Improve Heart Failure Outcomes trial tested an approach to telemonitoring that used existing technology; intervention patients (n = 826) were asked to measure their weight daily using a digital scale and to relay measurements using their telephone keypads. First, we estimated the number of weights subject to end-digit preference by dividing the weights by five and comparing the resultant distribution with the uniform distribution. Then, we assessed the characteristics of patients reporting an excess number of weights ending in 0 or 5, adjusting for chance reporting of these values.ResultsOf the 114,867 weight readings reported during the trial, 18.6% were affected by end-digit preference, and the likelihood of these errors occurring increased with the number of days that had elapsed since trial enrolment (odds ratio per day: 1.002, p < 0.001). At least 105 patients demonstrated end-digit preference (14.9% of those who submitted data); although statistical significance was limited, a pattern emerged that, compared with other patients, they tended to be younger, male, high school graduates and on more medications. Patients with end-digit preference reported greater variability in weight, and they generated an average 2.9 alerts to the telemonitoring system over the six-month trial period (95% CI, 2.3 to 3.5), compared with 2.3 for other patients (95% CI, 2.2 to 2.5).ConclusionsAs well as overshadowing clinically meaningful changes in weight, end-digit preference can lead to false alerts to telemonitoring systems, which may be associated with unnecessary treatment and alert fatigue. In this trial, end-digit preference was common and became increasingly so over time. By applying fraud detection methods to electronic medical data, it is possible to produce clinically significant information that can inform the design of initiatives to improve the accuracy of reporting.Trial registrationClinicalTrials.gov registration number NCT00303212 March 2006.

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

“…The SMART study considered end-digit preference in self-reported BP measurements recorded by patients at home, although this was not in the context of a telemonitoring system. 27 Steventon et al 28 found evidence of end-digit preference in weight measures among patients with heart failure using telemonitoring. However, neither study had a comparator group using automatically transmitted data in which there was no possibility of data manipulation.…”

Use and reporting of Bland–Altman analyses in studies of self-reported versus measured weight and height

“…Some studies that did not use Bland-Altman methods have mentioned defined limits. Steventon et al [47] felt that for telemonitoring of heart failure patients, a change of even 2 pounds could be considered important [47]. Bowring et al [48] defined accurate report of height and weight as <2 cm and <2 kg difference between self-report and measured values, based in part on results from Brestoff et al [49].…”

Weight Surveillance and Heart Failure Self-assessment in Patients with Chronic Leg Wounds: A Pilot Study

“…The literature supports that a weight check for gradual weight change might help clinicians identify those at risk for increased fluid overload from HF decompensation and that such checks might reveal edema and weight fluctuations that sometimes go unnoticed. [9][10][11][12][13] It is not known whether weight checks with every wound care visit would improve wound healing. There is a lack of studies exploring the outcome of weight surveillance and HF management in chronic wound healing.…”

“…Subtle weight changes are associated with early signs of HF exacerbation 9 . Because patients may fail to notice significant lower extremity edema, 10 early symptoms of exacerbation, including weight gain and dyspnea, are red flags for clinicians to educate and encourage self-care 11–13 . Provider failure to engage patients and encourage participation in self-assessment and stigma leading to inaccurate reports of weight can prevent early identification of HF exacerbations, making it more difficult to effectively manage HF in the outpatient setting.…”