Dietary Antioxidants and Chronic Diseases-The Swedish National March Cohort

Aim: Among an initial sample of 43,880 men and women who participated in the Swedish National March Cohort in 1997 the investigators aimed to investigate the effect of dietary Non Enzymatic Antioxidant Capacity (NEAC), assessed by a validated food frequency questionnaire at baseline, on the risk of 1) myocardial infarction and 2) osteoarthritis.

Identification of cases: Incident cases of myocardial infarction (ICD-10 code I21) and osteoarthritis (ICD-10 M15-19) were identified through exact linkages to the Swedish registries of population, migration, death, cancer, and inpatient care, using the national registration numbers as identifiers.

Main methods: The investigators fitted Cox proportional hazards regression models with age as underlying time scale to estimate hazard ratios (HR) with 95% confidence intervals (95% CI) for each outcome of interest at different levels of dietary NEAC. The investigators fitted multiple imputation models based on chained equations to address missingness of confounder variables.

Exclusion criteria

Study 1:

• Incorrect national registration number
• Subjects who were <18 years
• Emigration before beginning of follow-up
• Death before beginning of follow-up
• Cancer diagnosis
• Any cardiovascular disease
• Extreme energy intake

Exclusion criteria

Study 2:

• Incorrect national registration number
• Subjects who were <40 years
• Emigration before beginning of follow-up
• Death before beginning of follow-up
• Osteoarthritis diagnosis
• Bone cancer- or metastases
• Joint injury or any arthropathy disease other than osteoarthritis
• Extreme energy intake