Barrett 2012.

Methods	Study design: randomised controlled trial Setting: outpatient clinic adults from University of Wisconsin Department of Family Medicine Country: USA Study period: 8‐week training in mindfulness meditation, matched; 8‐week training in moderate‐intensity sustained exercise, or observational control. For the analysis we used the exercise group and the control group. Methods of analysis: "ARI illness episode, severity was assessed once daily using a 24‐item version of the Wisconsin Upper Respiratory, Symptom Survey (WURSS). The WURSS‐24 adds items assessing headache, body aches and fever to the well‐validated WURSS‐21. With each ARI illness episode, a nasal wash was collected within 3 days of symptom onset and analysed for interleukin‐8 (IL‐8), neutrophil count and viral nucleic acid. Elevated neutrophil count and IL‐8 levels are indicators of inflammation and correlate with symptom severity and viral shedding. Multiplex polymerase chain reaction (PCR) methods developed and validated at UW were used to identify respiratory viruses. Several validated self report questionnaires were used to explore potential explanatory pathways linking behavioural interventions to ARI outcomes SF‐12; PSS‐10; Positive and Negative Affect Schedule (PANAS); State Trait Anxiety Inventory (STAI); Life Orientation Test (LOT); Positive Relationships with Others (PR) scale. The Pittsburgh Sleep Quality Index (PSQI); The International Physical Activity Questionnaire (IPAQ); Mindful Attention Awareness Scale (MAAS). Health Care Utilization and Days of Work or School Missed" Statistical analysis: "the sample size of 150 was based on power estimates contrasting (1) meditation versus control and (2) exercise versus control. To control for multiple testing, P ≤ 0.025 cutoff for null hypothesis rejection was chosen. 1‐sided testing was justified by previously published research, all in the direction of positive results" "Unadjusted between‐group contrasts were calculated using 1‐sided t tests for continuous variables and proportional difference testing for binomials. Most participants did not experience ARI illness, therefore zero inflated regression models were used to control for potential confounders. These models take into account both logistic (incidence) and linear (days of illness or global severity) data. Covariates used in these models were age, sex, education, smoking status, body mass index, baseline physical and mental health (SF‐12) and cohort. Global severity was skewed, therefore Box‐Cox transformation was used for this outcome in these models. To explore potential causal pathways, we assessed the relationship of secondary outcomes measured just after interventions to the main outcomes"
Participants	Recruitment means: community‐targeted recruitment methods included advertising in local media Target participants: adults aged 50 years or over N randomised: 154 adults N completed: 149 adults completed: 47 (exercise), 51 (meditation), 51 (control) Gender M = 27: exercise 8, meditation 9, control 10 F = 122: exercise 39, meditation 42, control 41 Age: exercise (59.0 ± 6.6 years), meditation (60.0 ± 6.5 years), control (58.8 ± 6.8 years) Baseline details: age, gender, smoking, race, BMI, education, income and every questionnaire applied
Interventions	Description of intervention: weekly group sessions were divided into didactic instruction (cognitive, logistic, and behavioural) and practice (moderately intensive exercise using stationary bicycles, treadmills, and other equipment). For most participants, home exercise consisted of brisk walking or jogging. Mindfulness meditation: the standardised 8‐week MBSR course includes weekly 2½‐hour group sessions and 45 minutes of daily at‐home practice Exercise: (8 weeks), contact time (weekly 2½‐hour group sessions), home practice (45 minutes per day), and location Delivered by: exercise was applied by 3 qualified exercise instructors in clinical exercise physiology. Meditation was applied by instructors with advanced degrees, and all were trained in Massachusetts by the Kabat‐Zinn group. Intervention period: 8 weeks Follow‐up period: 9 months Co‐interventions: didactic instruction (cognitive, logistic, and behavioural)
Outcomes	Physical health, mental health (SF‐12) Negative emotion (PANAS); positive emotion (PANAS); optimism (LOT); social support (Ryff PR); perceived stress (PSS‐10); anxiety (current state) (STAI); sleep quality (PSQI); mindfulness (MAAS) Exercise, MET min/week (IPAQ) ARI illness burden: severity and duration (number of days), cold severity, symptoms, based on each ARI illness episode, global severity score (area under the curve (AUC)) for all ARI illness days; symptom severity and impact on function and quality of life Data collected (in 2 cohorts) over 7 or 9 months, but reported at 3 months.
Notes	Study funding: "this study was supported by a grant from the National Institutes of Health (NIH), National Center for Complementary and Alternative Medicine (1R01AT004313); and by a grant UL1RR025011 from the Clinical and Translational Science Award (CTSA) Program of the National Center for Research Resources, National Institutes of Health. Aleksandra Zgierska was supported by grant K23 AA017508 from National Institute on Alcohol Abuse and Alcoholism at NIH"
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"software... was used to generate 165 unique identification numbers in balanced blocks of 3."
Allocation concealment (selection bias)	Unclear risk	"Codes were concealed in consecutively numbered sealed envelopes, which were opened after consent to indicate allocation." No mention of envelopes being opaque
Blinding of participants and personnel (performance bias) All outcomes	High risk	The participants could not be blinded due to the characteristics of the intervention.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Outcome measurement is by participant self‐report, therefore cannot be blinded.
Incomplete outcome data (attrition bias) All outcomes	Low risk	For main outcomes data were missing for only 2 people.
Selective reporting (reporting bias)	Low risk	The study protocol is available, and the prespecified outcomes were published.
Other bias	Low risk	The study seems to be free of other sources of bias.