title: Validation of a short questionnaire for estimating dietary calcium intakes.
abstract: Concern about calcium supplements, and mainly minor side effects (e.g. constipation) impacting on compliance, means that assessing dietary calcium intake is important. There is no suitable biomarker. Compared to food diaries, a short questionnaire was an efficient way of confirming that patients had adequate calcium intakes (>700 or >1,000 mg)
  
  
  BACKGROUND
  Calcium is usually given alongside treatments for osteoporosis, but recent concerns about potential side effects have led to questioning whether supplements are always necessary. It is difficult to assess calcium intake in a clinical setting and be certain that the patient is getting enough calcium. The aim of this study was to determine whether a short questionnaire for estimating dietary calcium intakes in a clinical setting was fit for purpose.
  
  
  METHODS
  We assessed dietary calcium intakes using a short questionnaire (CaQ) in patients attending an osteoporosis clinic (n = 117) and compared them with calcium intakes obtained from a 7-day food diary (n = 72) and a food frequency questionnaire (FFQ) (n = 33).
  
  
  RESULTS
  Mean (SD) daily calcium intakes from the CaQ were 836 (348) mg; from the diaries, 949 (384) mg; and from the FFQ, 1,141 (387) mg. The positive predictive value (PPV) was >80% for calcium cut-offs > 700 mg and 70% for cut-offs > 1,000 mg. The calcium intakes for the false positives results were not far below the cut-off. For 1,200 mg, the PPV was 67% or less.
  
  
  CONCLUSIONS
  The CaQ is an adequate tool for assessing whether a patient has daily calcium intakes above 700 or 1,000 mg; if below these cut-offs, it is possible that the patient still has enough calcium in the diet, which could be clarified by questioning the patient further. As there were few patients with calcium intakes above 1,200 mg a day, the CaQ cannot be recommended as a tool for confirming higher dietary calcium intakes.
authors.affiliation: School of Medicine and Dentistry, University of Aberdeen, Foresterhill, Aberdeen, AB252ZD, UK, h.macdonald@abdn.ac.uk.
authors.forename: H M
authors.initials: HM
authors.lastname: Macdonald
authors.forename: A
authors.initials: A
authors.lastname: Garland
authors.forename: J
authors.initials: J
authors.lastname: Burr
authors.forename: A
authors.initials: A
authors.lastname: Strachan
authors.forename: A D
authors.initials: AD
authors.lastname: Wood
authors.forename: N A
authors.initials: NA
authors.lastname: Jamil
authors.forename: D
authors.initials: D
authors.lastname: McLernon
authors.forename: A J
authors.initials: AJ
authors.lastname: Black
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002136:Calcium, Dietary / Q000008:administration & dosage*; D015930:Diet Records; D005189:False Positive Reactions; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000178:diet therapy*; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D055815:Young Adult
chemical_list: D002136:Calcium, Dietary