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6th May 2022
The detection of emphysema via visual or quantitative assessment on a CT-scan has been found to be linked with a higher odds of developing lung cancer. This was the conclusion of a systematic review by researchers from the Departments of Epidemiology, Radiology and Pulmonary Diseases, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
The World Health Organization reported that in 2020 there were 2.21 million cases of lung cancer which resulted in 1.8 million deaths. A chest computer tomography (CT) scan enables quantification of the amount of emphysema present in the lungs and while some evidence suggests that emphysema on a CT scan is related to lung cancer in a high-risk population, other data indicates that no CT measures of emphysema have an independent association with lung cancer.
With some uncertainty over the association between the presence of emphysema seen on a CT scan and lung cancer, for the present study, the researchers decided to undertake a systematic review and meta-analysis to further probe this association. They searched all the major databases and included studies that specifically assessed the association between emphysema and the diagnosis of lung cancer based on histopathologic examination. The team defined visual emphysema as disrupted lung vasculature and parenchyma with low attenuation occupying any lung zone on the chest CT scan and quantitative emphysema as the percentage of total lung volume below a given Hounsfield unit threshold (-950 HU at full inspiration). They also sought to examine whether the severity of emphysema was associated with lung cancer and graded this as trace, mild, moderate/severe. The studies were stratified based on whether visual or quantitative assessments were used and the presence of confirmed lung cancer was the main outcome of interest expressed and expressed as an odds ratio, adjusted for age, gender and smoking status.
Emphysema and lung cancer risk
A total of 21 studies met the inclusion criteria with 3907 patients who had lung cancer and 103,175 controls.
The pooled odds ratio (OR) for lung cancer in the presence of emphysema was 2.3 (95% CI 2 – 2.6) in studies which employed visual assessment and 2.2 (95% CI 1.8 – 2.8) where the authors used quantitative assessment.
When stratified by disease severity, the overall pooled OR for lung cancer increased with disease severity although there were differences based on whether the data was acquired by visual or quantitative assessment. For example, in studies that employed visual assessment, the ORs for lung cancer were 2.5 (trace disease), 3.7 (mild disease) and 4.5 (moderate to severe disease). While these odds ratios were still elevated based on quantitative assessments, the magnitudes were slightly lower e.g., 1.9 for trace disease and 2.5 (moderate to severe disease).
Based on their findings, the author concluded that the presence of emphysema diagnosed on a chest CT scan was independently associated with a higher odds of developing lung cancer.
Yang X et al. Association between Chest CT–defined Emphysema and Lung Cancer: A Systematic Review and Meta-Analysis Radiology 2022
Adding coronary artery calcium scores (CACS) to further assess an individual’s cardiovascular risk assessment does not appear to be associated with any clinical benefit. This was the main finding of a systematic review and meta-analysis by a team from the School of Public Health, University of Sydney, Sydney, Australia.
Cardiovascular risk assessment is a critical step in the current approach to primary prevention of heart disease and is calculated using tools such as QRISK. Cardiac computed tomography (CT) imaging is an important tool for cardiovascular risk assessment in observational prospective studies and which provides a measure of subclinical disease such as coronary artery calcium. Moreover, the use of CACS has been shown to be an independent predictor of incident coronary heart disease among those deemed to be at intermediate-risk based on their Framingham risk score. The use of CACS screening has been found to improve medication adherence and provide superior coronary artery disease risk factor control without increasing downstream medical testing. By contrast, however, a study in post-menopausal women concluded that there was no independent benefit of coronary CT imaging in a low-to-moderate risk group.
With some uncertainty over whether addition of CACS derived from CT imaging provides an incremental benefit beyond that obtained from traditional risk assessment methods, in the current study, the Australian team undertook a systematic review and meta-analysis of available studies. They included studies in patients without existing cardiovascular disease, where at least one recognised risk calculator and a CACS had been used. The primary outcome as the change in C statistic for a model which contained the CACS compared to the base model without the CACS.
Coronary artery calcium scores and improvement in CVD risk prediction
A total of 6 studies with 17,961 individuals and 1043 cardiovascular events were included in the analysis. The studies varied in sample size from 470 to 5185 and mean ages ranged from 50 to 75.1 years (38.4 to 59.4% female).
The C statistic for cardiovascular disease (CVD) risk models but without CACS ranged from 0.693 to 0.80. Inclusion of CACS improved the pooled C statistic by 0.036.
When CACS was added, among participants whose risk was reclassified from low to intermediate or high risk, 85.5% to 96.4% did not experience an event during follow-up (ranging from 5.1 to 10 years). Among those who were reclassified from high risk to low risk by CACS, a similarly high proportion, 91.4% to 99.2% did not have a CVD event during follow-up.
The authors suggested that while CACS did appear to provide modest further discriminatory power to traditional risk factor assessments, this additional gain needed to be balanced against the higher costs and radiation risks. They concluded that while there were gains from inclusion of CACS, which patients might benefit remains to be determined and that there is no evidence to suggest that use of CACS offers a clinical benefit.
Bell KJL et al. Evaluation of the Incremental Value of a Coronary Artery Calcium Score Beyond Traditional Cardiovascular Risk Assessment: A Systematic Review and Meta-analysis JAMA Intern Med 2022
27th April 2022
The first-pass success rate is no better during endotracheal intubation whether patients are in the inclined or supine position. This was the conclusion of a systematic review by a team from the Department of Emergency Medicine, Indiana University School of Medicine, Indiana, USA.
Tracheal intubation is a procedure that is commonly performed outside of an operating theatre and has been found to be associated with higher risk than intubation in theatre. Performance of endotracheal intubation in the sitting or inclined position has been described as a useful technique for rapid airway control in the patient for whom maintenance of the upright posture is desirable. Although the use of the inclined position was described more than 30 years ago, research in 2016 demonstrated that placing patients in a back-up head-elevated position, compared with supine position, during emergency tracheal intubation was associated with a reduced odds of airway-related complications. However, not all studies have been positive with one 2017 randomised trial concluding that the ramped (inclined) position did not improve oxygenation during endotracheal intubation of critically ill adults compared with the sniffing (supine) position. A 2021 systematic review on the comparative merits of the inclined vs supine condition for tracheal intubation which set the primary outcomes as a successful first attempt at intubation, the number of tracheal intubation attempts and adverse events, found favourable aspects of the inclined compared to the supine position. However, the review did not include any emergency department studies and for the present review, the US team sought to examine the association between the inclined and supine positioning on first-pass success across a range of clinical settings.
The team searched for trials comparing both positions and used the first-pass success, which is a widely reported metric, as the primary outcome of interest. Several secondary outcomes including hypoxia, hypotension, mortality and time to intubation were also examined.
First-pass success and endotracheal intubation
A total of 10 studies with 18,371 intubations were included in the analysis and studies were randomised, prospective/observational and retrospective in nature though only two studies were undertaken in an emergency department.
The quality of the evidence with respect to the primary outcome of interest, first-pass success, was rated as low. Nevertheless, when comparing the two positions, there was no difference in the primary outcome (relative risk, RR = 1.02, 95% CI 0.98 – 1.05). In addition, there were also no significant differences for the secondary outcomes such as hypoxaemia (RR = 0.87, 95% CI 0.48 – 1.51), hypotension (RR = 1.33, 95% CI 0.77 – 2.29) and mortality (RR = 0.81, 95% CI 0.62 – 1.04).
The authors concluded that their review had demonstrated no evidence of either benefits or harm associated with the inclined versus supine positioning during an endotracheal intubation in any setting. However, they recognised that the overall quality of the evidence was rated as low or very low for most of the outcomes.
Turner JS et al. Effect of inclined positioning on first-pass success during endotracheal intubation: a systematic review and meta-analysis Emerg Med J 2022
22nd April 2022
Early computed tomography (ECT) is probably the best approach to ruling out a subarachnoid haemorrhage (SAH) in most patients who present at an emergency department (ED) with a sudden onset, severe headache. This was the conclusion of a systematic review by a team from the Centre for Reviews and Dissemination, University of York, York, UK.
A headache is one of the most common neurological symptoms and in one emergency department study, a primary headache disorder was diagnosed in 45.3% of patients (chiefly migraine) whereas life-threatening secondary headaches accounted for less than 2% of cases. Life-threatening secondary headache causes include SAH. The initial assessment of patients can be undertaken with an early computed tomography (ECT) scan, within 6 hours, which has been found to be extremely sensitive in ruling out aneurysmal SAH. However, other methods including lumbar puncture and the Ottawa SAH rule can also be used.
For the present study, the UK researchers undertook a systematic review of the evidence on diagnostic strategies for neurologically intact patients who presented to an ED with a non-traumatic, sudden onset severe headache that reached its maximum intensity within 1 hour. They searched for studies which assessed any care pathway for ruling out SAH in patients presenting at an ED with a sudden onset severe headache.
Early computed tomography and SAH diagnosis
A total of 37 studies were included with 13 assessing the Ottawa SAH rule, 4 assessing ECT and others which examined the value of lumbar puncture as well as spectrophotometric cerebrospinal fluid analysis.
The Ottawa SAH rule had an extremely high sensitivity, 99.5% (95% CI 90.8 – 100%) but a low specificity, 24% (95% CI 15.5 – 34.4%). Thus, strict application of this rule would have a false positive rate of 76% leading to further tests.
For ECT, within 6 hours of the onset of a headache, the sensitivity was 98.7% and the specificity 100%. However, this sensitivity was reduced for a CT scan undertaken longer than 6 hours after the onset of a headache, with a pooled sensitivity of 94.1% (95% CI 91 – 96.2%) though the specificity remained at 100%.
Both lumbar puncture and CSF spectrophotometric analysis (both used after a negative CT scan) had a sensitivity of 100% and a specificity of 95%.
Commenting on these findings, the authors suggested that the Ottawa SAH rule does little to aid the clinical decision-making for patients with a sudden onset severe headache, due to the high level of false positives, prompting the need for further investigation with a CT and/or lumbar puncture, increasing both healthcare costs and greater rates of adverse effects and CT exposure for patients.
They concluded that assuming availability, ECT appears sufficient to rule out SAH in the vast majority of patients who present with sudden onset, severe headaches. While later CT scans are less sensitive, lumbar puncture is more likely to be of benefit to patients where the suspicion of SAH remains.
Walton M et al. Management of patients presenting to the emergency department with sudden onset severe headache: systematic review of diagnostic accuracy studies Emerg Med J 2022
21st April 2022
The risk of depression can be greatly reduced even by undertaking lower amounts of the recommended levels of physical activity according to the results of a meta-analysis by researchers from the MRC Epidemiology Unit, University of Cambridge School of Clinical Medicine, Cambridge, UK.
Depression is a common, global mental disorder that is believed to affect 5% of the population. Moreover, a 2015 meta-analysis estimated that every year, 14.3% of global deaths, approximately 8 million deaths, can be linked to mental disorders. With such a high prevalence and associated mortality, much needs to be done to try and prevent or reduce depression risk. One possible mitigating factor is physical activity and according to one systematic review, promoting physical activity may serve as a valuable mental health promotion strategy in reducing the risk of developing depression. In fact, a 2018 meta-analysis of prospective cohort studies suggested that the available evidence supports the idea that physical activity can confer protection against the emergence of depression regardless of age and geographical region. With a good deal of evidence indicating a protective effect from physical activity, what remains uncertain is the strength or shape of the association between physical activity and depression.
For the present analysis, the UK team looked for trials that included any dimension of physical activity at three or more exposure levels, with at least 3,000 participants and with a follow-up period of not less than 3 years. Levels of physical activity were measured as marginal metabolic equivalents task hours per week (mMet-h/wk), where 1 Met represented the resting metabolic rate and 8.8 mMet-h/week was equivalent to the recommended weekly amount of physical activity. The outcome of interest was depression, major depressive disorder and elevated depression symptoms.
Depression risk and physical activity levels
The literature review identified 15 eligible publications including 191,130 participants (64% women) contributing 28,806 incident depression events and 2,110,588 person-years.
The results suggested an inverse and curvilinear dose-response between physical activity and depression, such that relative to adults who did not report undertaking any physical activity, those doing at least half of the recommended activity (4.4 mMet-hrs/week), had an 18% lower risk of depression (relative risk, RR = 0.82, 95% CI 0.77 – 0.87). Among those achieving the recommended amounts of activity (8.8 mMet-hrs/week), there was a 25% reduced risk of depression (RR = 0.75, 95% CI 0.68 – 0.82) and this reduction was the same for major depression and slightly lower for elevated depressive symptoms (RR = 0.73). However, interestingly, there was little apparent benefit derived from increasing activity to 17.5 mMet-hrs/week (RR = 0.72, 95% CI 0.64 – 0.81), for each of the three outcome measures.
Using potential impact fraction (PIF) analysis, the authors calculated that around 11.5% of incident depression could have been prevented in adults who achieved at least 8.8 mMet-hrs/week of physical activity.
Translating their findings into practical advice, the authors stated that accumulating an activity equivalent to 2.5 hours/week of brisk walking was associated with a 25% lower risk of depression and that achieving half of this level, reduced the risk by 18% compared with those who undertook no physical activity.
They concluded that substantial mental health benefits accrue from the achievement of physical activity levels even below those currently recommended.
Pearce M et al. Association Between Physical Activity and Risk of Depression: A Systematic Review and Meta-analysis JAMA Psychiatry 2022
19th April 2022
The cardiac data such as heart rate and rhythm obtained from a smartphone watch might not be as accurate for individuals with a darker skin tone. This was the conclusion of a systematic review by researchers from the University of Toronto, Canada, presented at the American College of Cardiology Conference 2022.
Cardiovascular disease is a leading global health issue and associated with an increasingly large economic burden. Technological innovations have become ingrained into everyday life and consumers are beginning to use consumer-grade software, such as smart wearables with numerous sophisticated sensors, to provide health insights. Today, commercial wearables can be used to collect cardiac data through electrocardiography (ECG) or photoplethysmography (PPG) and PPG has become the most popular technique for heart rate measurement. On the wrist, PPG detects blood flow rates by capturing the light intensity reflected from skin based on LEDs and photodetectors. However, questions have arisen over the accuracy of heart rate monitoring devices based on differences in skin tone. For example, because PPG detects changes in a beam of green light directed at the skin and since darker skin contains more melanin, it absorbs more green light than lighter skin. Moreover, previous research demonstrated that inaccurate PPG heart rate measurements occur up to 15% more frequently in dark skin as compared to light skin. In addition, pulse oximeter technology, which is also employed in smartwatches can be less accurate in darker skin as shown in one study, where Black patients had nearly three times the frequency of occult hypoxaemia, that was not detected by pulse oximetry as in White patients.
With smartwatches being used for health monitoring, for the present study, the team undertook a systematic review to determine the accuracy of cardiac data by wrist-worn wearable devices for participants of varying skin tones. They included studies in which heart rate and rhythm data were stratified according to the participant’s race and/or skin tone, which was measured using the Fitzpatrick score, which ranges from 1 to 6, with higher scores reflecting darker skin.
Cardiac data and skin tone
The literature search identified 10 studies with a total of 469 participants and the frequency-weighted Fitzpatrick score was reported in 6 of these studies, with 293 patients and the overall mean score was 3.5 (i.e., from the range of 1 – 6).
In 40% of studies, the researchers found a significant reduction in accuracy of heart rate measurements with a wearable device in those with darker skin compared to individuals with lighter skin tones and/or the gold standard measurements such as an ECG or a chest strap. Interestingly, one study found that wearable devices recorded significantly fewer data points for people with darker skin tones, despite no discrepancy in heart rate accuracy. A single study assessed ECG changes and noted a significant reduction in the accuracy of the R-R interval measurements in people with darker skin compared to ECG data (r = 0.98, p < 0.05).
Commenting on these findings, the lead author, Daniel Koerber, said “People need to be aware that there are some limitations for people with darker skin tones when using these devices, and the results should be taken with a grain of salt,” He added that “algorithms are often developed in homogeneous white populations, which may lead to results that are not as generalisable as we would like. Ongoing research and development of these devices should emphasise the inclusion of populations of all skin tones so that the developed algorithms can best accommodate for variations in innate skin light absorption.”
Koerber D et al. The effect of skin tone on accuracy of heart rate measurement in wearable devices: A systematic review. J Am Coll Cardiol 2022
8th April 2022
A systematic review has identified a low incidence of COVID-19 among the offspring of mother infected with the virus confirming mother to child transmission though the extent of this positivity is strongly affected by several maternal factors. This was the conclusion of a study by researchers from the WHO Collaborating Centre for Global Women’s Health, Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK.
The transplacental transmission of COVID-19 from infected mothers is known to occur. Moreover, there is evidence from a systematic review in 2021 that vertical transmission of COVID-19 is possible but that it only occurs in a minority of cases of maternal infection in the third trimester. Although COVID-19 antibodies have been identified in human milk, the timing of infection is not always clear, i.e., whether an infant became infected within the uterus or soon after birth.
For the present living systematic review, researchers set out to determine the rates of COVID-19 positivity in babies who were born to mothers infected with the virus and the timing of infection. In addition, they also sought to examine whether there were specific maternal factors associated with infection in babies, for example, illness severity in the mother.
The team undertook a comprehensive literature review and included studies of pregnant and recently pregnant women who sought hospital care for any reason but who had a positive diagnosis of COVID-19 infection and where the infection status of their offspring was also reported.
Low incidence of COVID-19 in offspring
The authors included 472 studies, 206 cohort and 266 case series and case reports with 28,952 mothers and 18,237 babies.
Based on PCR confirmed positivity, there was a low incidence of COVID-19 (1.8%, 95% CI 1.2 – 2.5%) among all the 14, 271 babies born to mothers who were infected with the virus.
There was also low level of IgM COVID-19 antibodies (2.6%, 95% CI 0.5 – 5.6%) detected in babies who were tested. In mothers who tested positive in the antenatal period, the positivity rate was 1.3% and 0.9% among babies tested within the first 24 hours of birth.
Overall, in 592 positive babies for which information on the timing of exposure was available, 14 had a confirmed mother to child transmission, 7 in utero, 2 intrapartum and 5 during the early postnatal period. Additionally, among 800 COVID-19 positive babies with outcome data, 20 were stillbirths, 23 were neonatal deaths, and 8 were early pregnancy losses.
The researchers identified several important maternal factors associated with a postnatal diagnosis of COVID-19. In particular, the presence of severe COVID-19 infection in mothers (odds ratio, OR = 2.36), maternal admission to an intensive care unit (OR = 3.46) and maternal death (OR = 14.09) were all significantly linked to a higher risk of positivity among offspring. However, the timing of maternal infection, i.e., post or antenatal, had no significant effect on offspring positivity.
The authors concluded that there was a low incidence of COVID-19 in babies born to mothers infected with the virus and that while vertical transmission is possible, it occurred at a low level.
Allotey J et al. SARS-CoV-2 positivity in offspring and timing of mother-to-child transmission: living systematic review and meta-analysis BMJ 2022
6th April 2022
The fracture detection rates are comparable for artificial intelligence (AI) and clinicians according to the findings of a meta-analysis by researchers from the Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, Oxford, UK.
Fractures represent a common reason for admission to hospital around the world. However, research suggests that fortunately, fracture rates have stabilised. For example, one 2019 UK-based study observed that the risk of admission for a fracture between 2004 and 2014 was 47.8 per 10,000 population but that the rate of fracture admission remained stable. Unfortunately, however, fractures are not always detected on first presentation as witnessed by a two-year study in which 1% of all visits resulted in an error in fracture diagnosis and 3.1% of all fractures were not diagnosed at the initial visit. One solution to improve upon the diagnostic accuracy of fractures is the use of artificial intelligence systems and in particular, machine learning, which enables algorithms to learn from data. Related to machine learning is deep learning, which is a more sophisticated approach to machine learning that uses complex, multi-layered “deep neural networks. Deep learning systems hold great potential for the detection of fractures and in a 2020 review, the authors concluded that deep learning was reliable in fracture diagnosis and had a high diagnostic accuracy.
For the present meta-analysis, the Oxford team further assessed and compared the diagnostic performance of AI and clinicians on both radiographs and computed tomography (CT) images in fracture detection. The team searched for studies that developed and or validated a deep learning algorithm for fracture detection and assessed AI vs clinician performance during both internal and external validation. The team analysed receiver operating characteristic curves to determine both sensitivity and specificity.
Fracture detection rates of AI and clinicians
A total of 42 studies with a median number of 1169 participants were included, 37 of which included fractures detected on radiographs and 5 with CT. A total of 16 studies compared the performance of the AI against expert clinicians, 7 to experts and non-experts and one compared AI to non-experts.
When evaluating AI and clinician performance in studies of internal validation, the pooled sensitivity was 92% (95%CI 88 – 94%) for AI and 91% (95% CI 85 – 95%) for clinicians. The pooled specificity values were also broadly similar with a value of 91% of AI and 92% for clinicians.
For studies looking at external validation, the pooled sensitivity for AI was 91% (95% CI 84 – 95%) and 94% (95% CI 90 – 96%) for clinicians on matched sets. The specificity was slightly lower for AI compared to clinicians (91% vs 94%).
The authors concluded that AI and clinicians had comparable reported diagnostic performance in fracture detection and suggested that AI technology has promise as a diagnostic adjunct in future clinical practice.
Kuo RYL et al. Artificial Intelligence in Fracture Detection: A Systematic Review and Meta-Analysis Radiology 2022
31st March 2022
The use of music interventions appear to be associated with clinically meaningful improvements in mental and a smaller improvement in physical health-related quality of life. However, the specific type of music intervention providing the greatest benefit remains unclear. This was the conclusion from a meta-analysis of studies by researchers from the Institute of Music Physiology and Musicians’ Medicine, Hannover University of Music, Hannover, Germany.
The use of music interventions (MIs) such as listening to music, playing an instrument or singing, has been shown to positively impact on the global and social functioning of patients with mental health conditions such as schizophrenia. Furthermore, there is also reliable evidence for the positive effects of music and singing on wellbeing (related to the positive aspects of a person’s life) in adults without underlying mental health problems. Other evidence from an umbrella review of performing arts as a health resource, concluded that positive health effects were associated with as little as 30 to 60 minutes of performing arts participation.
The CDC in the US defines health-related quality of life (HRQOL) as an individual’s or a group’s perceived physical and mental health over time. HRQOL can be assessed using dedicated questionnaires, including the 36-item Health Survey Short Form (SF-36) and related, reduced 12-item Health Survey Short Form (SF-12). Moreover, both the SF-36 and 12 have been used in studies of music interventions.
Although music interventions appear to give rise to improvements in both HRQOL and well-being, what remains unclear is the associations between different types of MIs and changes in HRQOL as measured using both the SF-36 and SF-12. This was the purpose of the current study and the German team included randomised and non-randomised trials that investigated music making (singing, listening, playing music) interventions and which reported changes in SF-36 or SF-12, before and after the intervention. The researchers focused on both the mental component summary (MCS) and the physical component summary (PCS) of the SF-36 or SF-12 since higher scores in each of these domains were indicative of better mental and physical HRQOL. The threshold mean difference in MCS scores was set as a mean difference of 3 or more.
Music interventions and MCS and PCS scores
The literature search identified 26 eligible studies with 779 participants (mean age = 60 years) and which comprised listening to music, music therapy, singing with one study exploring the effect of gospel music.
Overall, a music intervention was associated with a significant decrease in both MCS (total mean difference, TMD = 2.95, p < 0.01) and PCS scores (TMD = 1.09, p = 0.02) compared to pre-intervention values.
In subgroup analysis, in which MIs were added to usual treatment, there was a significant increase in MCS scores vs usual treatment alone (TMD = 3.72, 95% CI 0.40 – 7.05) but not for PCS. However, it was not possible to identify any important differences based on the type of musical intervention.
The authors concluded that while MIs led to a significant increase in mental HRQOL, the changes in PCS were equivocal. They added that given the variation in the effect of the different interventions such as singing, listening to music etc, it was not possible to provide any firm recommendations about the optimal intervention or dosage for use in specific clinical scenarios.
McCrary JM et al. Association of Music Interventions With Health-Related Quality of Life: A Systematic Review and Meta-analysis JAMA Netw Open 2022
21st March 2022
Replacing beverages containing no-calorie sweeteners instead of sugar in overweight or obese patients with, or at risk of, diabetes, leads to reduction in cardiometabolic risk factors such as body weight and body mass index. This was the finding of network meta-analysis by researchers from St Michael’s Hospital, Toronto, Canada.
Research suggests that the habitual consumption of sugar-containing drinks is associated with adverse cardiovascular outcomes such as a greater incidence of type 2 diabetes, as well as heart, kidney and non-alcoholic liver disease, tooth decay and gout. Moreover, a 2013 systematic review identified how drinking sugar-sweetened beverages also promotes weight gain in both children and adults.
The use of no-calorie sweeteners instead of sugar-containing drinks could theoretically ameliorate these adverse sequelae. However, a meta-analysis of 35 observational studies assessing the impact on outcomes such as body mass index and fasting blood glucose, concluded that most health outcomes did not seem to differ between the non-sugar sweeteners exposed and unexposed groups. Furthermore, in a recent American Heart Association (AHA) science advisory published in 2018, it was stated that there is a dearth of evidence on the potential adverse effects of low calorie sweeteners (LCS) relative to potential benefits although the AHA did concluded that on the basis of the available evidence, it is prudent to advise against prolonged consumption of LCS beverages by children. The group also added that the use of other alternatives to sugar sweetened beverages should focus on plain water.
For the present study, the Canadian team used a network meta-analysis to enable both sugar-containing beverages and water to be used as comparators and used no-calorie sweeteners as a replacement for water as the reference substitution. Included studies were randomised controlled trials of at least 2 weeks duration. The primary outcome was a change in body weight and several secondary outcomes were used including measures of such as body mass index (BMI), glycaemic control and changes in blood pressure.
No-calorie sweeteners and cardiovascular health outcomes
A total of 17 randomised controlled trials with 1733 adults (mean age 33.1 years, 77.4% female) who were either overweight or obese or who had diabetes or were at risk of developing the condition were included in the network meta-analysis. The trials had a median sample size of 72 participants.
For the replacement of sugar containing drinks with no-calorie sweeteners, there was a reduction in body weight, with a pooled standard mean difference (SMD) of -0.65 (95% CI – 1.05 to – 0.25), a reduced body mass index (SMD = – 0.67, 95% CI -1.19 to – 0.14) and percent body fat (SMD = -0.74), all of which were significant and favoured the no-calorie sweeteners. In contrast, changes in glycated haemoglobin and fast plasma glucose changes were non-significant.
Interestingly, when water was used as a substitute for sugar-sweetened beverages, there was no significant impact for each of outcomes measured although the direction of the associations did favour water in most cases. When no-calorie sweeteners were substituted for water, there was a greater reduction in body weight (SMD = -0.48, 95% CI -0.88 to -0.08) for the no-calorie sweeteners though none of the other outcomes was significant apart from systolic blood pressure (SMD = -0.78, 95% CI -1.40 to -0.16).
The authors concluded that using no-calorie sweeteners for sugar-containing beverages appeared to be associated with a reduction in body weight and other cardiometabolic risk factors and that there was no evidence of harm. They suggested that the use of no-calorie-sweeteners was a potentially useful strategy for overweight/obese adults with, or at risk of, diabetes.
McGlynn ND et al. Association of Low- and No-Calorie Sweetened Beverages as a Replacement for Sugar-Sweetened Beverages With Body Weight and Cardiometabolic Risk: A Systematic Review and Meta-analysis JAMA Netw Open 2022