Follow-up methods, including weight assessments and AF case definition
| First author (year) | Follow-up (years) | When weight change was assessed | How weight change was assessed | AF case definition | Relative timing of weight and AF assessment | AF incidence per 1000 person years |
| Rosengren et al 29 | Maximum 34.3 | Single midlife evaluation (at 12 years after screening appointment) where weight was measured and participants reported their recalled weight at age 20 years. | Weight change between recalled weight at age 20 and midlife evaluation (approximately 30-year interval). | Hospital discharge code for AF | Weight change calculated at single midlife evaluation visit (1970–1973). AF incidence recorded over subsequent study follow-up to 31 December 2004. Median time between midlife evaluation and discharge for AF was 25 years. | 7.5 |
| Tedrow et al 24 | Mean 12.9 | Self-reported weight on the 24, 36, 60, 72and 108 month questionnaires during the randomised trial, at the beginning of the observational phase and yearly thereafter. Self-reported height used to calculate BMI. | BMI change over the first 60 months of the study (5-year interval). | Participant self-reporting, triangulated against electronic health record | Weight change in first 60 months of study and AF incidence after that time period through to the end of the study. | 1.9 |
| Grundvold et al 23 | Maximum 35 | Measured weight at baseline visit and recalled weight at age 25 years recorded at that time. Baseline visits 1972 to 1975. | Weight change between recalled weight and baseline (approximately 25 year interval). | ECG at study visit and hospital discharge codes | Weight change calculated at baseline visit based on change from recalled weight aged 25 years. AF incidence over subsequent follow-up, up to 31 December 2007. | 4.5 |
| Huxley et al 30 | Maximum 11 | Weight change between baseline and visit four (9-year interval) | Weight was measured at baseline and at 3, 6 and 9 years later. | ECG at study visit and codes from hospital discharge and death certificates | Weight change and AF incident cases across same study follow-up period. | 6.9 |
| Alonso et al 21 | Mean 9 | Weight was measured at baseline and annually thereafter. Measurements done in duplicate using a digital scale and stadiometer. | Weight change was between baseline and first annual visit (1-year interval) | ECG at biannual follow-up visit and hospital discharge codes | Weight change in first year of study with AF incidence calculated across follow-up, including the first year. | 6.4 |
| Grundvold et al 22 | Mean 4.6 | Weight was measured at baseline and at a second visit within 18 months. | Weight change was between the two visits (average intervals were 421, 396 and 402 days for the weight gain, stable weight and weight loss categories, ie, around 13–14 months) | Codes from national patient registries and primary care electronic database | Follow-up for AF started after the second visit and continued until new AF diagnosis, death or 31 December 2009. | 9.8* |
| Johnson et al 25 | Mean 22.3 (from rescreening) 28.3 (from baseline) | Weight was measured at two screening examinations, separated by an average of 6 years (first 1974–1984, second 1981–1985). | Average annual weight change was calculated. | Hospital inpatient and outpatient codes | Weight change between first and second screening examinations, AF incidence between second screening examination and study endpoint, 31 December 2010. | 8.5* |
| Berkovitch et al 28 | Mean 6.4 | Weight was measured at annual visits. | The weight change between visits was integrated into the Cox model as a time-dependent variable. | ECG at study visit, Holter monitor or primary care electronic records | Weight change and AF incidence both reported across same study follow-up period. | 2.5* |
| Diouf et al 27 | Mean 5 | Weight was measured at baseline (in 1999/2000) and a second visit (in 2004/2005). | Weight change between the two visits (approximately 5-year interval) | Single study follow-up ECG | Weight change and AF incidence both reported across same study follow-up period. | 2.0 |
| Ball et al 26 | Mean 15.7 | BMI was measured at each study survey. Participants visited a study centre and were weighed in light clothing with no shoes for consistency. | Change in BMI between the third (1986–1987) and fourth (1994–1995) survey | Hospital inpatient and outpatient records, linked with National Causes of Death Registry | Weight change between third and fourth survey used to calculate BMI change. Incidence of AF calculated over subsequent follow-up after fourth survey to 31 December 2013. | 3.6 |
AF, atrial fibrillation; BMI, body mass index.