Research news in brief

Real-time flu prediction may be possible using wearable heart rate and sleep tracking devices

The first study to evaluate de-identified data from wearable devices on resting heart rate and sleep has found improved real-time prediction of influenza-like illness compared to current surveillance methods based on data from Fitbit users from five US states. The research, published in The Lancet Digital Health, demonstrates the potential of data from wearable devices to improve surveillance of infectious disease. Resting heart rate tends to spike during infectious episodes and this is captured by wearable devices such as smartwatches and fitness trackers, that track heart rate. The US researchers reviewed de-identified data from 200 000 users who wore a Fitbit wearable device that tracks users’ activity, heart rate and sleep for at least 60 days during the study time from March 2016 to March 2018. From the 200 000, 47,248 users wore a Fitbit device consistently during the study period, resulting in a total of 13 342 651 daily measurements evaluated. Users’ average resting heart rate and sleep duration were calculated, as well as deviations to this to help identify when these measures were outside of an individual’s typical range (ie, using standard deviation). During each week, a user was identified as abnormal if their weekly average resting heart rate was above their overall average (by more than a half or a full standard deviation) and their weekly average sleep was not below their overall average (by more than half a standard deviation). The users were arranged by which state they lived in, and the proportion of users above the threshold each week was calculated. This data was compared to weekly estimates for influenza-like illness rates reported by the US Centers for Disease Control. By incorporating data from Fitbit trackers, influenza predictions at the state level were improved. In all five states there was an improvement in real-time surveillance , with an average increase in Pearson correlation of 0·12 (SD 0·07) over baseline models, corresponding to an improvement of 6·3–32·9%;  the closest alignment with CDC data was found when abnormal resting heart rate was defined as half a standard deviation above normal and sleep more than half a standard deviation below.

Falling risk of heart disease among survivors of child cancer diagnosed since the 1970s

There has been a measurable decline in serious heart conditions among adult survivors of childhood cancer diagnosed since the 1970s, according to a study published in The BMJ. The findings suggest that efforts to reduce exposure to the most toxic effects of anticancer treatment, including radiotherapy, seem to be working. Many adult survivors of childhood cancer are at risk of early death and long term health conditions related to treatment. For example, cardiac radiation can cause heart and circulatory problems in later life. In recent years, cancer therapy has focused on improving cure rates while trying to minimise long term adverse effects, but the impact of these changes in survivors is not clear. To fill this evidence gap, researchers from St Jude Children’s Research Hospital in Tennessee in the US, set out to assess whether these changes are associated with altered risks for cardiac events among adult survivors. Their findings are based on more than 23 000 adults from the Childhood Cancer Survivor Study who had survived the most common childhood cancers, diagnosed before age 21 and treated in the 1970s, 1980s and 1990s. Using questionnaires, five cardiac conditions – heart failure, coronary artery disease (narrowing of arteries), heart valve defects (valvular disease), damage to the heart tissue lining (pericardial disease) and heart rhythm problems (arrhythmias) – were recorded. Cardiovascular risk factors, such as diabetes, high blood pressure and cholesterol levels, smoking, exercise and weight, were also recorded. The number of survivors exposed to cardiotoxic chemotherapy increased in more recent decades, but the proportion receiving higher doses decreased. Exposure to cardiac radiation declined from 77% of survivors treated in the 1970s to 40% treated in the 1990s. After taking account of potentially influential factors, risk of coronary artery disease decreased significantly from 0.38% in the 1970s to 0.24% in the 1980s and 0.19% in the 1990s (P<0.01), although there was no reduction in  valvular disease (0.06%, 0.06%, 0.05%), pericardial disease (0.04%, 0.02%, 0.03%), or arrhythmias (0.08%, 0.09%, 0.13%). The reduction in coronary artery disease was largely accounted for by reduction in cardiac radiation, particularly among survivors of Hodgkin lymphoma. Traditional cardiovascular risk factors high cholesterol and blood pressure also strongly increased the risk for most cardiac conditions, providing important insights to help improve outcomes for cancer survivors, note the authors.

Buyer beware: probiotic online health claims dubious

A new study, published in Frontiers in Medicine, cautions that while Google is adept at sorting the most reliable websites to the top of the list, the majority of websites providing information on probiotics are from commercial sources. The public should be wary of searching for probiotic information online as most webpages originate from unreliable sources and the health-benefit claims are often not supported by robust scientific evidence. Concerned that the public has unrealistic expectations about the beneficial effects of probiotics (bolstered by online claims and hype in the news), researchers from the Université libre de Bruxelles in Belgium decided to assess the information that the public were exposed to when searching online. They assessed the first 150 webpages brought up by a Google search for “probiotics”, recorded where they originated from and the diseases they mentioned. The scientific evidence for health benefits of probiotics against these diseases were then examined for scientific rigour. The researchers used the Cochrane library to assess the strength of scientific evidence found online. They also looked at how Google ranked these websites. News outlets and commercial sources made up the majority of the 150 webpages and the analysis showed these were the least reliable, often not mentioning the side effects in immunocompromised individuals nor any regulatory issues. In addition, the findings of experiments on mice were used to make claims about probiotic benefits against disease in humans.

What’s new online at the MJA

Ethics and law: Victoria’s Voluntary Assisted Dying Act: navigating section 8
Moore et al; doi: 10.5697/mja2.50437
Section 8 is an unwarranted infringement on communication between health practitioners and their patients … PREMIUM CONTENT

Research: Second primary cancers in people who had cancer as children: an Australian Childhood Cancer Registry population-based study
Youlden et al; doi: 10.5697/mja2.50245
Survivors of childhood cancer remain at increased risk of a second primary cancer well into adulthood … OPEN ACCESS permanently