Associations of obesity, physical activity level, inflammation and cardiometabolic health with COVID-19 mortality: a prospective analysis of the UK Biobank cohort

Mortality risk in patients with obesity and COVID-19 infection: a systematic review and meta-analysis

Obesity is a risk factor for severe respiratory diseases, including COVID-19 infection. Meta-analyses on mortality risk were inconsistent. We systematically searched 3 databases (Medline, Embase, CINAHL) and assessed the quality of studies using the Newcastle-Ottawa tool (CRD42020220140). We included 199 studies from US and Europe, with a mean age of participants 41.8-78.2 years, and a variable prevalence of metabolic co-morbidities of 20-80 %. Exceptionally, one third of the studies had a low prevalence of obesity of <20 %. Compared to patients with normal weight, those with obesity had a 34 % relative increase in the odds of mortality (p-value 0.002), with a dose-dependent relationship. Subgroup analyses showed an interaction with the country income. There was a high heterogeneity in the results, explained by clinical and methodologic variability across studies. We identified one trial only comparing mortality rate in vaccinated compared to unvaccinated patients with obesity; there was a trend for a lower mortality in the former group. Mortality risk in COVID-19 infection increases in parallel to an increase in BMI. BMI should be included in the predictive models and stratification scores used when considering mortality as an outcome in patients with COVID-19 infections. Furthermore, patients with obesity might need to be prioritized for COVID-19 vaccination.

The dose-response relationship between physical activity and the risk of death from pneumonia in middle-aged and older adults: A meta-analysis

BACKGROUND

Deaths from COVID-19 are concentrated in older adults, and studies have reported that physical activity (PA) can reduce the risk of death from pneumonia.

METHODS

Eight cohort studies and 2 case-control studies were included according to the inclusion and exclusion criteria established in this meta-analysis study followed the PRISMA guideline, 8 cohort studies and 2 case-control studies were finally included. Then, the research objects in these studies were classified to further study the dose-response relationship and non-dose-response relationship.

RESULTS

The highest dose of PA reduced the risk of death by 59% (risk ratio = 0.41; 95% confidence interval: 0.23-0.58) compared with the lowest dose of PA in middle-aged and elderly people. Furthermore, when the PA level was <10 m/wk, the risk of death from pneumonia was reduced by 6% every 4.5 MET-h/wk increase. At a PA level > 10 m/wk, the risk of death from pneumonia increased by 5% every 4.5 MET-h/wk increase. At a PA level > 30 m/wk, PA is a risk factor for pneumonia-related death in middle-aged and elderly people.

CONCLUSIONS

This meta-analysis showed that PA was associated with a reduced risk of dying from pneumonia in middle-aged and older adults, and that there was a significant nonlinear negative dose-response relationship between PA levels and the risk of dying from pneumonia. Therefore, moderate exercise was recommended.

Obesity and mortality in patients with COVID-19: A meta-analysis of prospective studies

BACKGROUND AND OBJECTIVES

Previous prospective studies have reported inconsistent findings on the associ-ation between obesity and mortality in patients with COVID-19. This study aimed to investigate the associa-tion between them by using a meta-analysis of prospective studies.

METHODS AND STUDY DESIGN

We searched PubMed and EMBASE to retrieve studies using keywords related to this topic on January 3, 2022. Data were extracted for a random-effects meta-analysis to calculate a pooled odds ratio (OR), relative risk (RR), or hazard ratio (HR) with a 95% confidence interval (CI).

RESULTS

In the meta-analysis of 15 prospective cohort studies, obesity significantly increased the risk of mortality in patients with COVID-19 (OR/RR/HR, 1.52; 95% CI, 1.26 to 1.84; I2 = 90.4%). Most of the included studies were conducted in European (n = 10) and North American (n = 4) countries. In the subgroup meta-analysis by continent, there was a significant association between them in European countries (OR/RR/HR, 1.78; 95% CI, 1.30 to 2.43; I2 = 81.4%). Also, in the subgroup meta-analysis by data source, obesity was significantly associated with the increased mortality in patients with COVID-19 in both population- and hospital-based data.

CONCLUSIONS

We found that obesity is associated with the increased risk of mortality in patients of COVID-19.

Association between physical activity and risk of COVID-19 infection or clinical outcomes of the patients with COVID-19: A systematic review and meta-analysis

Objective

The COVID-19 pandemic has caused serious consequences for global health and economy. The important question is whether the level of physical activity might influence the risk of COVID-19 incidence or clinical outcomes, including the severity or mortality of infected patients. The objective of this systematic review and meta-analysis is to evaluate the association between sufficient physical activity and incidence, hospitalization, severity, recovery, and mortality of COVID-19.

Methods

A systematic search of Web of Sciences, PubMed, and Scopus between December 2019 and November 2021 was conducted. Studies were screened based on the inclusion criteria, i.e. observational studies (case-control, prospective or retrospective longitudinal designs, and cross-sectional studies) which have determined the association of physical activity, exercise, sports participation, or sedentary behavior with COVID-19 incidence or outcomes, including mortality, severity, recovery and hospitalization in healthy population or population with any specific comorbidity.

Results

Based on eligibility criteria, 27 articles were finally included in the qualitative synthesis. The meta-analysis of five studies evaluating the association of physical activity and COVID-19 mortality showed a weighted OR of OR of 0.61 (CI 95%: 0.50-0.75) with heterogeneity (I2 = 45.8%, P < 0.001) and in seven studies regarding physical activity and COVID-19 hospitalization, weighted OR was 0.541 (CI 95%: 0.491-0.595) with heterogeneity (I2 = 81.7%, P < 0.001).

Conclusion

Participating in sufficient physical activity might decrease COVID-19 related COVID-19-related hospitalization and mortality. Developing programs to increase physical activity during the COVID-19 pandemic might be an appropriate health strategy.

Comorbid asthma decreased the risk for COVID-19 mortality in the United Kingdom: Evidence based on a meta-analysis

The study aimed to investigate the influence of comorbid asthma on the risk for mortality among patients with coronavirus disease 2019 (COVID-19) in the United Kingdom (UK) by utilizing a quantitative meta-analysis. The pooled odds ratio (OR) with 95% confidence interval (CI) was estimated by conducting a random-effects model. Sensitivity analysis, I² statistic, meta-regression, subgroup analysis, Begg's analysis and Egger's analysis were all implemented. Our results presented that comorbid asthma was significantly related to a decreased risk for COVID-19 mortality in the UK based on 24 eligible studies with 1,209,675 COVID-19 patients (pooled OR = 0.81, 95% CI: 0.71-0.93; I² = 89.2%, P < 0.01). Coming through further meta-regression to seek the possible cause of heterogeneity, none of elements might be responsible for heterogeneity. A sensitivity analysis proved the stability and reliability of the overall results. Both Begg's analysis (P = 1.000) and Egger's analysis (P = 0.271) manifested that publication bias did not exist. In conclusion, our data demonstrated that COVID-19 patients with comorbid asthma might bear a lower risk for mortality in the UK. Furthermore, routine intervention and treatment of asthma patients with severe acute respiratory syndrome coronavirus 2 infection should be continued in the UK.

Effect of replacing television viewing with different intensities of physical activity on COVID-19 mortality risk: Short communication from UK Biobank

AIMS

This study aimed to examine the theoretical effects of replacing television (TV) viewing with different intensities of physical activity on COVID-19 mortality risk using isotemporal substitution models.

METHODS

The analytical sample was composed of 359,756 UK Biobank participants. TV viewing and physical activity were assessed by self-report. Logistic regressions adjusted for covariates were used to model the effects of substituting an hour a day of TV viewing with an hour of walking, moderate-intensity physical activity (MPA) or vigorous-intensity physical activity (VPA) on COVID-19 mortality risk.

RESULTS

From 16 March 2020 to 12 November 2021, there were 879 COVID-19 deaths in the analytical sample. Substituting an hour a day of TV viewing with an hour of walking was associated with a 17% lower risk of COVID-19 mortality (odds ratio (OR)=0.83, 95% confidence interval (CI) 0.74-0.92). In sex-stratified analyses, the same substitution was associated with a lower risk in both men (OR=0.85, 95% CI 0.74-0.96) and women (OR=0.78, 95% CI 0.65-0.95). However, replacing an hour a day of TV viewing with an hour of MPA was only associated with a lower risk in women (OR=0.80, 95% CI 0.65-0.98).

CONCLUSIONS

Replacing TV viewing with walking was associated with a significant reduction in COVID-19 mortality risk. Public health authorities should consider promoting the replacement of TV viewing with walking as a protective strategy against COVID-19 mortality.

Baseline physical activity and the risk of severe illness and mortality from COVID-19: A dose-response meta-analysis

To provide a scientific basis for improved exercise-based immunity, a meta-analysis was used to explore the dose-response relationship between physical activity (PA) and the risk of severe illness and mortality related to COVID-19 (coronavirus disease 2019). To this end, we searched PubMed, Web of Science databases from January 2020 through April 2022. 14 observational studies met the criteria for inclusion in the meta-analysis, including 2840 cases of severe illness and death from COVID-19. Categorical dose-relationship analysis showed that the risks of severe illness and mortality from COVID-19 were, respectively, 46% (risk ratio (RR): 0.54; confidence intervals (CIs): 0.41-0.68) and 59% (RR = 0.41; 95%CI: 0.23-0.58) lower for the highest dose of PA compared with the lowest dose of PA. The results of the continuous dose-response analysis show an inverse nonlinear relationship (P_{non-linearity} < 0.05) between PA and both the risk of severe illness and mortality from COVID-19. For PA below 10 MET-h/week (MET-h/week: metabolic equivalent of task-hours/week), an increase of 4 MET-h/week (1 h of moderate-intensity or 0.5 h of high-intensity PA) was associated with 8% and 11% reductions in the risk of severe illness and mortality from COVID-19. PA above 10 MET-h/week lowered the risk of severe illness and mortality from COVID-19 by 7% and 9%, respectively, for each 4 MET-h/week increase. Doses of WHO-recommended PA levels (10 MET-h/week) may be required for more substantial reductions in the risk of severe illness and mortality from COVID-19.

A phenome-wide investigation of risk factors for severe COVID-19

With the continued spread of COVID-19 globally, it is crucial to identify the potential risk or protective factors associated with COVID-19. Here, we performed genetic correlation analysis and Mendelian randomization analysis to examine genetic relationships between COVID-19 hospitalization and 405 health conditions and lifestyle factors in 456 422 participants from the UK Biobank. The genetic correlation analysis revealed 134 positive and 65 negative correlations, including those with intakes of a variety of dietary components. The MR analysis indicates that a set of body fat-related traits, maternal smoking around birth, basal metabolic rate, lymphocyte count, peripheral enthesopathies and allied syndromes, blood clots in the leg, and arthropathy are causal risk factors for severe COVID-19, while higher education attainment, physical activity, asthma, and never smoking status protect against the illness. Our findings have implications for risk stratification in patients with COVID-19 and the prevention of its severe outcomes.

COVID-19: Reducing the risk via diet and lifestyle

This review shows that relatively simple changes to diet and lifestyle can significantly, and rapidly, reduce the risks associated with coronavirus disease 2019 (COVID-19) in terms of infection risk, severity of disease, and even disease-related mortality. A wide range of interventions including regular exercise, adequate sleep, plant-based diets, maintenance of healthy weight, dietary supplementation, and time in nature have each been shown to have beneficial effects for supporting more positive health outcomes with COVID-19, in addition to promoting better overall health. This paper brings together literature from these areas and presents the argument that non-pharmaceutical approaches should not be overlooked in our response to COVID-19. It is noted that, in several cases, interventions discussed result in risk reductions equivalent to, or even greater than, those associated with currently available vaccines. Where the balance of evidence suggests benefits, and the risk is minimal to none, it is suggested that communicating the power of individual actions to the public becomes morally imperative. Further, many lives could be saved, and many harms from the vaccine mandates avoided, if we were willing to embrace this lifestyle-centred approach in our efforts to deal with COVID-19.

High grip strength attenuates risk of severe COVID-19 in males but not females with obesity: A short communication of prospective findings from UK Biobank

We examined the joint associations of BMI category and grip strength tertile with risk of severe COVID-19 (inpatient COVID-19 or COVID-19 mortality) in 327 500 UK Biobank participants. Compared to normal-weight males with high grip strength, the odds ratio (95 % confidence interval) for males with obesity with low grip strength was 2.39 (1.59-3.60), but 1.52 (0.98-2.35) for males with obesity with a high grip strength. A higher grip strength did not appear to be associated with lower risk of severe COVID-19 in females. Muscle mass and strength development should be considered as a means to reduce risk of severe COVID-19 for males with obesity.

Television Viewing Time, Overweight, Obesity, and Severe COVID-19: A Brief Report From UK Biobank

BACKGROUND

Overweight and obesity are well-established risk factors for COVID-19 severity; however, less is known about the role of sedentary behaviors such as television (TV) viewing. The purpose of this brief report was to determine whether lower TV viewing time may mitigate the risk of severe COVID-19 in individuals with excess weight.

METHODS

We analyzed 329,751 UK Biobank participants to investigate the independent and combined associations of BMI and self-reported TV viewing time with odds of severe COVID-19 (inpatient COVID-19 or COVID-19 death).

RESULTS

Between March 16 and December 8, 2020, there were 1648 instances of severe COVID-19. Per 1-unit (hours per day) increase in TV viewing time, the odds of severe COVID-19 increased by 5% (adjusted odds ratio = 1.05, 95% confidence interval = 1.02-1.08). Compared with normal-weight individuals with low (≤1 h/d) TV viewing time, the odds ratios for overweight individuals with low and high (≥4 h/d) TV viewing time were 1.17 (0.89-1.55) and 1.66 (1.31-2.11), respectively. For individuals with obesity, the respective ORs for low and high TV viewing time were 2.18 (1.61-2.95) and 2.14 (1.69-2.73).

CONCLUSION

Higher TV viewing time was associated with higher odds of severe COVID-19 independent of BMI and moderate to vigorous physical activity. Additionally, low TV viewing time may partly attenuate the elevated odds associated with overweight, but not obesity.

Effects of physical activity on the severity of illness and mortality in COVID-19 patients: A systematic review and meta-analysis

Purpose: This systematic review and meta-analysis investigated the association between Physical activity (PA) before Coronavirus Disease 2019 (COVID-19) infection and the severity of illness and mortality in COVID-19 patients.

Methods: A comprehensive search was undertaken to identify retrospective and nonrandomized controlled trial studies comparing the severity and mortality of COVID-19 infection among COVID-19 patients who had previously reported their participation in PA with those who had not. The databases searched were PubMed, Cochrane Library, Scopus, Science Direct, EMBASE, OPENGREY.EU, and ClinicalTrials.gov. The risk of bias was assessed using the Newcastle-Ottawa Scale. A random-effects model was used for determining pairwise meta-analyses. The protocol was registered with PROSPERO (CRD42021262548).

Results: Eighteen studies met the inclusion criteria (5 cross-sectional, 12 cohort, and 1 case-control studies). All 1 618 680 subjects were adults. PA significantly decreased the risk of death in COVID-19 patients (odds ratio [OR] 0.34; 95% confidence interval [CI], 0.19–0.62; p < 0.001) and the risk of severe outcomes (OR 0.60; 95% CI, 0.48–0.76; p < 0.001). Subgroup analysis showed that PA for ≥150 min/wk at a moderate intensity or ≥75 min/wk at a vigorous intensity reduced the risks of severity and mortality. Vigorous PA reduced mortality risk, whereas moderate to vigorous PA reduced the risks of severity and mortality.

Conclusion: PA before infection might reduce severity and mortality in COVID-19 patients, especially PA ≥ 150 min/wk of moderate activity or ≥75 min/wk of vigorous activity. However, careful interpretations should be considered due to the difference in PA patterns and severity definitions among included studies. This finding implies that engaging in regular PA, even in different patterns, has beneficial effects on the severity and mortality of COVID-19 patients.

Physical activity lowers the risk for acute respiratory infections: Time for recognition

Physical inactivity is a well-established risk factor for chronic diseases, such as cardiovascular disease, cancer, and diabetes mellitus. There is a growing awareness that physical inactivity should also be regarded as a risk factor for acute respiratory infections (ARIs). ARIs, such as the common cold, influenza, pneumonia, and coronavirus disease 2019 (COVID-19), are among the most pervasive diseases on earth and cause widespread morbidity and mortality. Evidence in support of the linkage between ARIs and physical inactivity has been strengthened during the COVID-19 pandemic because of increased scientific scrutiny. Large-scale studies have consistently reported that the risk for severe COVID-19 outcomes is elevated in cohorts with low physical activity and/or physical fitness, even after adjusting for other risk factors. The lowered risk for severe COVID-19 and other ARIs in physically active groups is attributed to exercise-induced immunoprotective effects, including enhanced surveillance of key immune cells and reduced chronic inflammation. Scientific consensus groups, including those who submitted the Physical Activity Guidelines for Americans, have not yet given this area of research the respect that is due. It is time to add "reduced risk for ARIs" to the "Exercise is Medicine" list of physical activity-related health benefits.

The role of physical activity in the clinical outcomes of people diagnosed with Covid-19: A systematic review

Objective

This review aimed to compile the evidence on PA and clinical outcomes of people receiving a positive diagnosis of covid-19.

Design

Systematic review.

Methods

The search was performed in five databases: EMBASE, MEDLINE via PubMed portal, Scopus, SPORTDiscus via EBSCO platform, and Web of Science. In addition, the "gray" literature was searched through Google Scholar and medRxiv published between January 2020 and July 2022. Studies were assessed for risk of bias, with the extraction of relevant data. Our search revealed a total of 10,028 studies.

Results

After applying the eligibility criteria 32 studies were included. Thirty-one studies were at low to moderate risk of bias. Physically active individuals, who were diagnosed with covid-19, presented attenuation of clinical outcomes, such as decreased risk of hospitalization, recovery time, number of symptoms, severity, and ICU and death when compared to individuals with low levels of PA or classified as sedentary.

Conclusions

Physically active individuals when diagnosed with covid-19 may have decreased risk of several clinical outcomes related to covid-19, including but not limited to hospitalization and number of symptoms. Public health authorities should develop strategies and initiatives that promote safe PA environments to improve the clinical prognosis of people diagnosed with covid-19.

Study registration

Open Science Framework (OSF), DOI registry 10.17605/OSF.IO/PV6NF. It can be consulted through the access link: https://doi.org/10.17605/OSF.IO/PV6NF, October 07, 2021.

The joint associations of physical activity and TV viewing time with COVID-19 mortality: An analysis of UK Biobank

We used logistic regression to investigate the joint associations of physical activity level (high: ≥3000 MET-min/week, moderate: ≥600 MET-min/week, low: not meeting either criteria) and TV viewing time (low: ≤1 h/day, moderate: 2-3 h/day, high: ≥4 h/day) with COVID-19 mortality risk in UK Biobank. Additional models were performed with adjustment for body mass index (BMI) and waist circumference. Within the 373, 523 included participants, there were 940 COVID-19 deaths between 16 March 2020 and 12 November 2021. Compared to highly active individuals with a low TV viewing time, highly active individuals with a high TV viewing time were at significantly higher risk of COVID-19 mortality (odds ratio = 1.54, 95% confidence interval = 1.11-2.15). However, the greatest risk was observed for the combination of a low physical activity level and a high TV viewing time (2.29, 1.63-3.21). After adjusting for either BMI or waist circumference, only this latter combination remained at a significantly higher risk, although the effect estimate was attenuated by 43% and 48%, respectively. In sum, a high TV viewing time may be a risk factor for COVID-19 mortality even amongst highly active individuals. Higher adiposity appears to partly explain the elevated risk associated with a low physical activity level and a high TV viewing time.

Impact of influenza vaccination on GP-diagnosed COVID-19 and all-cause mortality: a Dutch cohort study

OBJECTIVES

As clinical presentation and complications of both viruses overlap, it was hypothesised that influenza vaccination was associated with lower general practitioner (GP)-diagnosed COVID-19 rates and lower all-cause mortality rates.

STUDY DESIGN

From a primary care population-based cohort in the Netherlands, GP-diagnosed COVID-19 (between 10 March and 22 November 2020) and all-cause mortality events (between 30 December 2019 and 22 November 2020) were recorded. 223 580 persons were included, representing the influenza vaccination 2019 target group (all aged ≥60 years, and those <60 years with a medical indication). Proportional hazards regression analyses evaluated associations between influenza vaccination in 2019 and two outcomes: GP-diagnosed COVID-19 and all-cause mortality. Covariables were sex, age, comorbidities and number of acute respiratory infection primary care consultations in 2019.

RESULTS

A slightly positive association (HR 1.15; 95% CI 1.08 to 1.22) was found between influenza vaccination in 2019 and GP-diagnosed COVID-19, after adjusting for covariables. A slightly protective effect for all-cause mortality rates (HR 0.90; 95% CI 0.83 to 0.97) was found for influenza vaccination, after adjusting for covariables. A subgroup analysis among GP-diagnosed COVID-19 cases showed no significant association between influenza vaccination in 2019 and all-cause mortality.

CONCLUSIONS

Our hypothesis of a possibly negative association between influenza vaccination in 2019 and GP-diagnosed COVID-19 was not confirmed as we found a slightly positive association. A slightly protective effect on all-cause mortality was found after influenza vaccination, possibly by a wider, overall protective effect on health. Future research designs should include test-confirmed COVID-19 cases and controls, adjustments for behavioural, socioeconomic and ethnic factors and validated cause-specific mortality cases.

Baseline physical activity is associated with reduced mortality and disease outcomes in COVID-19: A systematic review and meta-analysis

Among coronavirus disease 2019 (COVID-19) patients, physically active individuals may be at lower risk of fatal outcomes. However, to date, no meta-analysis has been carried out to investigate the relationship between physical activity (PA) and fatal outcomes in patients with COVID-19. Therefore, this meta-analysis aims to explore the hospitalisation, intensive care unit (ICU) admissions, and mortality rates of COVID-19 patients with a history of PA participation before the onset of the pandemic, and to evaluate the reliability of the evidence. A systematic search of MEDLINE/PubMed, Cumulative Index to Nursing and Allied Health Literature, Scopus, and medRxiv was conducted for articles published up to January 2022. A random-effects meta-analysis was performed to compare disease severity and mortality rates of COVID-19 patients in physically active and inactive cases. Twelve studies involving 1,256,609 patients (991,268 physically active and 265,341 inactive cases) with COVID-19, were included in the pooled analysis. The overall meta-analysis compared with inactive controls showed significant associations between PA with reduction in COVID-19 hospitalisation (risk ratio (RR) = 0.58, 95% confidence intervals (CI) 0.46-0.73, P = 0.001), ICU admissions (RR = 0.65, 95% CI 0.52-0.81, P = 0.001) and mortality (RR = 0.47, 95% CI 0.38-0.59, P = 0.001). The protective effect of PA on COVID-19 hospitalisation and mortality could be attributable to the types of exercise such as resistance exercise (RR = 0.27, 95% CI 0.15-0.49, P = 0.001) and endurance exercise (RR = 0.41, 95% CI 0.23-0.74, P = 0.003), respectively. Physical activity is associated with decreased hospitalisation, ICU admissions, and mortality rates of patients with COVID-19. Moreover, COVID-19 patients with a history of resistance and endurance exercises experience a lower rate of hospitalisation and mortality, respectively. Further studies are warranted to determine the biological mechanisms underlying these findings.

Physical activity and risk of infection, severity and mortality of COVID-19: a systematic review and non-linear dose-response meta-analysis of data from 1 853 610 adults

OBJECTIVE

To quantify the association between physical activity and risk of SARS-CoV-2 infection, COVID-19-associated hospitalisation, severe illness and death due to COVID-19 in adults.

DESIGN

A systematic review and meta-analysis.

DATA SOURCES

Three databases were systematically searched through March 2022.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Peer-reviewed articles reporting the association between regular physical activity and at least one COVID-19 outcome in adults were included. Risk estimates (ORs, relative risk (RR) ratios or HRs) were extracted and pooled using a random-effects inverse-variance model.

RESULTS

Sixteen studies were included (n=1 853 610). Overall, those who engaged in regular physical activity had a lower risk of infection (RR=0.89; 95% CI 0.84 to 0.95; I2=0%), hospitalisation (RR=0.64; 95% CI 0.54 to 0.76; I2=48.01%), severe COVID-19 illness (RR=0.66; 95% CI 0.58 to 0.77; I2=50.93%) and COVID-19-related death (RR=0.57; 95% CI 0.46 to 0.71; I2=26.63%) as compared with their inactive peers. The results indicated a non-linear dose-response relationship between physical activity presented in metabolic equivalent of task (MET)-min per week and severe COVID-19 illness and death (p for non-linearity <0.001) with a flattening of the dose-response curve at around 500 MET-min per week.

CONCLUSIONS

Regular physical activity seems to be related to a lower likelihood of adverse COVID-19 outcomes. Our findings highlight the protective effects of engaging in sufficient physical activity as a public health strategy, with potential benefits to reduce the risk of severe COVID-19. Given the heterogeneity and risk of publication bias, further studies with standardised methodology and outcome reporting are now needed.

PROSPERO REGISTRATION NUMBER

CRD42022313629.

Impact of contextual factors on patient outcomes following conservative low back pain treatment: systematic review

Background and objective

Chronic low back pain is pervasive, societally impactful, and current treatments only provide moderate relief. Exploring whether therapeutic elements, either unrecognised or perceived as implicit within clinical encounters, are acknowledged and deliberately targeted may improve treatment efficacy. Contextual factors (specifically, patient’s and practitioner’s beliefs/characteristics; patient-practitioner relationships; the therapeutic setting/environment; and treatment characteristics) could be important, but there is limited evidence regarding their influence. This research aims to review the impact of interventions modifying contextual factors during conservative care on patient’s pain and physical functioning.

Databases and data treatment

Four electronic databases (Medline, CINAHL, PsycINFO and AMED) were searched from 2009 until 15th February 2022, using tailored search strategies, and resulted in 3476 unique citations. After initial screening, 170 full-text records were potentially eligible and assessed against the inclusion–exclusion criteria. Thereafter, studies were assessed for methodological quality using a modified Downs and Black scale, data extracted, and synthesised using a narrative approach.

Results

Twenty-one primary studies (N = 3075 participants), were included in this review. Eight studies reported significant improvements in pain intensity, and seven in physical functioning, in favour of the contextual factor intervention(s). Notable contextual factors included: addressing maladaptive illness beliefs; verbal suggestions to influence symptom change expectations; visual or physical cues to suggest pain-relieving treatment properties; and positive communication such as empathy to enhance the therapeutic alliance.

Conclusion

This review identified influential contextual factors which may augment conservative chronic low back pain care. The heterogeneity of interventions suggests modifying more than one contextual factor may be more impactful on patients’ clinical outcomes, although these findings require judicious interpretation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12998-022-00430-8.