Association between serum vitamin D status and health-related quality of life (HRQOL) in an older Korean population with radiographic knee osteoarthritis: data from the Korean national health and nutrition examination survey (2010-2011).
BACKGROUND
Vitamin D is important in bone health and its relationship with osteoarthritis has recently been reported. Both vitamin D deficiency and knee osteoarthritis are age dependent and are known to affect quality of life (QOL) in older populations. In this study, we aimed to determine the association between vitamin D status and health-related quality of life (HRQOL) in an older Korean population with knee osteoarthritis.


METHODS
A total of 2,165 participants aged ≥50 years with radiographic knee osteoarthritis defined as Kellgren-Lawrence (KL) grade ≥2 were selected from data from the 5th Korean National Health and Nutrition Examination Survey (KNHANES V), a representative cross-sectional nationwide survey conducted in 2010-2011. They stratified into two levels by vitamin D status (deficiency <10 ng/dL and normal ≥10 ng/dL). HRQOL was measured using the EuroQOL visual analogue scale (EQ-VAS) and the five dimensions and summary index of the EuroQOL-5 dimension (EQ-5D).


RESULTS
The vitamin D deficiency group was more likely to report problems with mobility, self-care, and usual activities. Vitamin D deficiency was significantly associated with poor HRQOL indicated by the lowest quartile of EQ-VAS (unadjusted odds ratio [OR] =1.832, p = 0.006) and the lowest quartile of the EQ-5D index (unadjusted OR = 1.992, p = 0.003). Theses associations of vitamin D status with EQ-VAS and EQ-5D index were maintained after adjustment for age and sex (Model 1: OR = 1.677, p = 0.022 and OR = 1.701, p = 0.021, respectively). The significant associations of vitamin D status with EQ-VAS were maintained after adjustment for other possible covariates (Model 3: OR = 1.562, p = 0.044). Also, a trend of associations between vitamin D status and EQ-5D index were shown after adjustment for other covariates (Model3: OR = 1.681, p = 0.056).


CONCLUSIONS
This is the first study to reveal that vitamin D status is independently associated with HRQOL in an older Korean population with knee osteoarthritis. Our results suggest that the maintenance of sufficient vitamin D status may be important to prevent QOL decline in older populations with knee osteoarthritis.
Department of Family Medicine, Severance Hospital, Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu, Seoul, 120-752, Republic of Korea. prayer322@chamc.co.kr.
Hye-Jung
HJ
Kim
Department of Family Medicine, Severance Hospital, Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu, Seoul, 120-752, Republic of Korea. jeeyon14@yuhs.ac.
Jee-Yon
JY
Lee
Department of Family Medicine, Severance Hospital, Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu, Seoul, 120-752, Republic of Korea. 114386@nhimc.or.kr.
Tae-Jong
TJ
Kim
Department of Family Medicine, Severance Hospital, Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu, Seoul, 120-752, Republic of Korea. INDI5645@yuhs.ac.
Ji-Won
JW
Lee
D000293:Adolescent; D000368:Aged; D000369:Aged, 80 and over; D015984:Causality; D002648:Child; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D051346:Mobility Limitation; D015596:Nutrition Assessment; D020370:Osteoarthritis, Knee / Q000097:blood* / Q000453:epidemiology* / Q000517:prevention & control / Q000523:psychology; D015995:Prevalence; D011788:Quality of Life; D056910:Republic of Korea / Q000453:epidemiology; D012648:Self Care; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology*
D014807:Vitamin D