NCT01880463.

Trial name or title	Dry eye disease in the vitamin D and omega‐3 trial (VITAL)
Methods	Study design: randomized, parallel‐group, controlled trial Study site(s): not reported Number randomized (total and per group): 25,875 participants Unit of randomization (individual or eye): not reported Exclusions after randomization: not reported Losses to follow‐up: not reported Number analyzed (total and per group): not reported Unit of analysis (individual or eye): not reported Reported power calculation? (Y/N): N Reported subgroup analysis? (Y/N): N
Participants	Participant characteristics Country: United States Age (mean ± SD, range): not reported Gender: not reported (males and females) Inclusion criteria: 1. All participants in VITAL (NCT 01169259) are eligible to participate in this ancillary study Exclusion criteria: 1. Not reported Equivalence of baseline characteristics? (Y/N): not reported
Interventions	Intervention #1: vitamin D (cholecalciferol, 2000 IU per day) plus fish oil placebo Intervention #2: vitamin D placebo, plus 1 capsule containing 840 mg of marine omega‐3 fatty acids (eicosapentaenoic acid 465 mg and docosahexaenoic acid 375 mg) Intervention #3: vitamin D placebo plus fish oil placebo Intervention #4: vitamin D (cholecalciferol, 2000 IU per day) plus 1 capsule containing 840 mg of marine omega‐3 fatty acids (eicosapentaenoic acid 465 mg and docosahexaenoic acid 375 mg) Length of follow‐up: 5 years Notes: none
Outcomes	Primary outcome(s): dry eye disease (report of a diagnosis of dry eye disease confirmed by medical record review) Secondary outcome(s): none specified Adverse events reported? (Y/N): not reported Measurement time points (specify intervals at which outcomes were assessed): not reported Other issues with outcome assessment (eg, quality control for outcomes, if any): none
Starting date	July 2010
Contact information	None provided
Notes	Recruitment status: unknown First posted: June 2013 Last post updated: January 2016