| Pre-intervention (Oct 2016–Mar 2017) | Post-intervention (Oct 2017–Mar 2018) | P value | |
| Total | 41 254 (100) | 26 336 (100) | <0.001 |
| Number of vitamin D requests | |||
| Requests with vitamin D <30 nmol/l | 15 358 (39.4) | 8810 (34.5) | <0.001 |
| Requests with vitamin D 30–50 nmol/l | 11 166 (28.6) | 8044 (31.5) | <0.001 |
| Requests with vitamin D >50 nmol/l | 12 469 (32.0) | 8671 (34.0) | <0.001 |
| Demographic characteristics | |||
| Age, years | 47.9 (20.5) | 46.5 (20.4) | <0.001 |
| Male | 13 914 (33.7) | 8512 (32.3) | <0.001 |
| Ethnicgroup | <0.001 | ||
| Caucasian | 20 103 (55.9) | 11 991 (54.8) | |
| Asian | 12 766 (35.5) | 8327 (37.3) | |
| Black | 1235 (3.4) | 845 (3.8) | |
| Other | 1890 (5.3) | 1194 (5.3) | |
| Biochemistry values | |||
| Vitamin D nmol/la | 36 (24–57) | 38 (26–58) | <0.001 |
| Calcium mmol/l | 2.26 (0.09) | 2.25 (0.09) | <0.001 |
| Phosphate mmol/la | 1.11 (1.10, 1.11) | 1.12 (0.99, 1.25) | <0.001 |
Values are n (%) or mean (standard deviation), apart from where indicated. Vitamin D levels were missing for 2261 requests made pre-intervention and 811 requests post-intervention. aMedian, interquartile range.