Table 2.
Linear regression model of factors associated with serum 25-hydroxyvitamin D (nmol/l) among New Zealand aged-care residents, February–September 2014
| Unadjusted model | Final adjusted model†,‡ | ||||||
|---|---|---|---|---|---|---|---|
| Variable * | n | Coefficient | 95 % CI | P | Coefficient | 95 % CI | P |
| Geographical location (South) | 292 | 8·3 | −5·0, 21·5 | 0·203 | 10·9 | 4·6, 17·1 | 0·002 |
| Sex (female) | 292 | 23·0 | 6·9, 39·1 | 0·008 | 8·9 | 1·7, 16·1 | 0·019 |
| Age (years) | 292 | 0·7 | −0·1, 1·5 | 0·079 | −0·2 | −0·5, 0·2 | 0·324 |
| Age × sex interaction | −0·1 | −0·9, 0·7 | 0·809 | ||||
| Season of blood collection (Autumn) | 292 | −3·1 | −17·8, 11·7 | 0·664 | – | −13·1, 0·7 | 0·076 |
| Time in residential aged-care (months) | 292 | 0·2 | −0·0, 0·2 | 0·057 | 0·2 | 0·0, 0·3 | 0·011 |
| eGFR (ml/min per 1·73 m2) | 290 | −0·3 | −0·5, −0·1 | 0·005 | −0·3 | −0·4, −0·1 | 0·001 |
| Serum AGP (g/l) | 290 | 12·8 | −6·1, 31·6 | 0·169 | 13·1 | 5·5, 20·7 | 0·002 |
| BMI categories | 286 | ||||||
| Underweight (<20 kg/m2) | 17·2 | −0·3, 34·6 | 0·053 | 8·5 | −7·1, 24·1 | 0·265 | |
| Overweight (25–29·99 kg/m2) | −10·7 | −22·8, 1·3 | 0·077 | −5·3 | −15·4, 4·7 | 0·276 | |
| Obese (≥30 kg/m2) | −8·2 | −22·1, 5·6 | 0·224 | −8·0 | −18·9, 2·9 | 0·137 | |
| Oral nutrition supplements (no/yes) | 292 | 28·6 | 13·3, 43·8 | 0·001 | 4·9 | −6·6, 16·4 | 0·376 |
| Current smoking status (no/yes) | 282 | −25·7 | −39·9, −11·4 | 0·002 | −7·8 | −29·5, 13·9 | 0·456 |
| Malnutrition§ | 286 | ||||||
| At risk of malnutrition | 10·2 | −0·2, 20·5 | 0·054 | 1·2 | −7·2, 9·6 | 0·766 | |
| Malnourished | 24·1 | 9·9, 38·4 | 0·003 | 2·5 | −9·4, 14·5 | 0·659 | |
| Frailty|| | 271 | ||||||
| Pre-frail | 6·7 | −10·0, 23·4 | 0·407 | ||||
| Frail | 5·4 | −12·9, 23·7 | 0·541 | ||||
| Vitamin D-inhibiting medications (no/yes) | 292 | −3·3 | −15·7, 9·1 | 0·581 | |||
| Funded vitamin D supplement¶ (no/yes) | 292 | 58·5 | 45·4, 71·7 | <0·001 | 71·8 | 61· 8, 81·7 | <0·001 |
| Other vitamin D-containing preparations (no/yes) | 292 | 22·6 | 11·0, 34·3 | 0·001 | 70·2 | 55·3, 85·2 | <0·001 |
| Funded × additional vitamin D interaction | –8·4 | –83·9, –32·8 | <0·001 | ||||
eGFR, estimated glomerular filtration rate; AGP, α1-acid glycoprotein.
Continuous variables presented as variable (unit); categorical variables presented as variable (yes/no); ordinal variables presented with the following reference categories: BMI, normal weight (20–24·99 kg/m2); malnutrition, normal nutrition status; frailty, not frail.
n 271, one resident taking calcitriol was excluded from final model; adjusted for variables with P≤0·20 or decided a priori (geographical location, age, season of blood collection, time in residential aged-care, inflammatory markers, BMI categories).
R 2 of the adjusted model =0·6918; constant =40·1 (95 % CI 0·0, 80·1); P=0·050.
Malnutrition by Mini Nutritional Assessment Short Form (MNA-SF) categories( 21 ).
Frailty coded by the Survey of Health, Ageing and Retirement in Europe Frailty Instrument (SHARE-FI)( 29 ).
Cholecalciferol 1250 µg (50 000 IU) once per month.