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Table 1 Classification of endpoints in 547 randomised controlled trials of vitamin D supplementation

From: Assessment of research waste part 1: an exemplar from examining study design, surrogate and clinical endpoints in studies of calcium intake and vitamin D supplementation

Endpointa Number of RCTs
Clinical endpoints
 Fracture 18
 Falls 17
 Respiratory (eg asthma, COPD, URTI) 14
 Musculoskeletal symptoms/Pain 11
 Pregnancy outcomes 9
 Tuberculosis 8
 Multiple Sclerosis 7
 Mood 6
 SLE/Rheumatoid Arthritis 6
 Other 41
Surrogate endpoints
 Bone mineral density 57
 25OHD only 49
 HbA1c or measures of glycaemia 42
 Blood pressure 38
 Basic biochemistry 37
 Bone turnover markers 31
 25OHD, vitamin D metabolites and/or PTH only 24
 Muscle Strength 16
 Body weight 15
 Physical performance tests 14
 Vascular properties 7
 Hepatitis C viral load 5
 Lung function tests 4
 Lipids 4
 Other laboratory tests/assays 51
 Other endpoints 16
  1. Abbreviations: COPD chronic obstructive pulmonary disease, URTI upper respiratory tract infection, SLE Systemic lupus erythematosus, 25OHD 25 hydroxyvitamin D, PTH parathyroid hormone
  2. amany trials reported more than 1 endpoint in the abstract. The most clinically relevant endpoint was used for each study