Vitamin D status among surgical orthopaedic patients in a private hospital in Johannesburg, South Africa

Vermaak, Ronelle Talana (2017-03)

Thesis (MNutr)--Stellenbosch University, 2017.

Thesis

ENGLISH SUMMARY : Introduction: Vitamin D is a fat-soluble vitamin, classified as 9.10-secosteroid hormone precursor. Current research has revealed that optimal vitamin D status may be essential for a range of skeletal and non-skeletal outcomes. Vitamin D status was defined as sufficient (>30ng/mL), insufficient (20–30ng/mL) and deficient (<20ng/mL) for the purpose of this study. Data on 25(OH)D in South African adults is limited and vitamin D status assessment in the pre-operative adult orthopaedic patient has not yet been done. This study aimed to determine the vitamin D status of orthopaedic surgical patients and the impact of the surgical intervention on vitamin D status after the recovery period, as well as to determine the relationship between vitamin D status and demographic parameters, anthropometrics, sun exposure and vitamin D intake. Methods: During the study period (April 2014–September 2014) patients were identified from orthopaedic surgical lists at Mulbarton Hospital, Johannesburg. Pre-operatively anthropometric measurements and relevant questionnaires (demographic, skin classification, sun exposure (calculated sun index) and short food questionnaire for vitamin D) were completed. Biochemical analysis of vitamin D was done pre-operatively. At a follow-up screening, vitamin D status, sun exposure and questionnaire for vitamin D intake were repeated. Results: A total of 67 patients (67.2% females) were included. Average age was 50.9 ±12.3 years. Mean BMI of males and females was 30.5kg/m² and 31.7kg/m² respectively. The majority of patients had white skin (67.2%) and the rest brown to dark brown skin (32.8%). The median calculated sun index pre-operatively and post-operatively was 0.715; this can be calculated as 38 minutes sun exposure three times per week on arms and legs. Vitamin D oral intake from food was 195IU/day, and with supplementation added, 202IU/day. More than 65% of the population had insufficient plasma vitamin D status of which 29.9% were deficient with a mean value of 26ng/mL(SD 9.6).Correlation of vitamin D status with gender, smoking, vitamin D oral intake and BMI was not statistically significant. There was a weak positive correlation (r=0.249) between age and vitamin D status. There was a significant difference in vitamin D status of white and brown skin tones (9.82ng/mL)(p=0.025). There was a moderate positive correlation between vitamin D status and calculated sun index (r=0.451)(p=0.017). Sun exposure can be seen as a positive predictive indicator of vitamin D status where a calculated sun index of 1.159 yield a sensitivity of 68.2% and specificity of 56.5% (p=0.054). There was no statistical significant change in sun exposure, vitamin D intake and vitamin D status after surgical intervention. Conclusion: Even with sun exposure higher than the current recommendation, 25(OH)D levels were still very low; thus it can be suggested that the current recommendation for sun exposure might need to be doubled to achieve sufficient levels of 25(OH)D. Minor orthopaedic surgical interventions do not negatively influence sun exposure habits, vitamin D intake and thus vitamin D status, but these patients might be considered to be an “at risk” group as their mean BMI classification is obese and elective orthopaedic surgery is indicated.

AFRIKAANSE OPSOMMING : Inleiding: Vitamien D is 'n vetoplosbare vitamien, geklassifiseer as 9,10-secosteroid hormoon voorloper. Huidige navorsing het aan die lig gebring dat optimale vitamien D status noodsaaklik is vir 'n verskeidenheid van skeletale en nie-skeletale uitkomste. Vitamien D status word gedefinieer as voldoende (>30ng/ml), onvoldoende (20–30ng/ml) en gebrekkig (<20ng/ml) vir die doel van hierdie studie. Data oor 25(OH)D in Suid-Afrika is beperk en status van volwasse ortopediese pre-operatiewe pasiënte nog nie bepaal nie. Hierdie studie het ten doel gehad om die vitamien D status van ortopediese chirurgie pasiënte te bepaal, die impak van die chirurgiese ingreep op vitamien D status ná intervensie asook die verhouding tussen vitamien D status en demografiese parameters, antropometrie, son blootstelling en vitamien D inname Metodes: Gedurende die studietydperk (April 2014–September 2014) was pasiënte geïdentifiseer vanaf die ortopediese chirurgiese lyste by Mulbarton hospitaal in Johannesburg. Pre-operatiewe antropometriese metings en relevante vraelyste (demografies, vel klassifikasie, sonblootstelling (berekende sonindeks) en ‘n voedsel vraelys vir vitamien D) is voltooi. Biochemiese ontleding van vitamien D is pre-operatief gedoen. Met die opvolg besoek is vitamien D status, sonblootstelling en vitamien D voedsel vraelys herhaal. Resultate: 'n Totaal van 67 pasiënte (67.2% vroue) was ingesluit. Gemiddelde ouderdom was 50.9 ±12.3 jaar. Gemiddelde liggaamsmassa-indeks (LMI) van mans en vrouens was 30.5kg/m² en 31.7kg/m² onderskeidelik. Die meerderheid van pasiënte het ‘n wit (67.2%) en die res ‘n bruin tot donkerbruin velkeur (32.8%) gehad. Die mediaan berekende sonindeks pre-operatief en post-operatief was 0.715; dit kan bereken word as 38 minute sonblootstelling drie keer per week op arms en bene. Gemiddelde orale inname van vitamien D vanaf voedsel was 195IU/dag, en met aanvullings 202IU/dag. Meer as 65% van die studiegroep het onvoldoende plasma vitamien D status gehad waarvan 29.9% gebrekkig was met 'n gemiddelde waarde van 26ng/ml(SD 9.6). Korrelasie tussen vitamien D status en geslag, rook gewoontes, orale vitamien D inname en LMI was nie statisties betekenisvol nie. Daar was 'n swak positiewe korrelasie (r=0.249) tussen ouderdom en vitamien D status. Daar was 'n beduidende verskil in 25(OH)D van respondente met ‘n wit en bruin velkleur (9.82ng/ml)(p=0.025). Daar was 'n matige positiewe korrelasie tussen 25(OH)D en berekende sonindeks (r=0.451) (p=0.017). Sonblootstelling kan gesien word as 'n positiewe aanwyser van vitamien D status. 'n Berekende sonindeks van 1.159 lewer ‘n sensitiwiteit van 68.2% en ‘n spesifisiteit van 56.5% (p=0.054) as ‘n aanwyser van voldoende vitamien D status. Daar was geen statisties beduidende verandering in sonblootstelling, vitamien D inname en vitamien D status na die chirurgiese ingryping nie. Gevolgtrekking: Selfs met sonblootstelling hoër as die huidige kliniese aanbeveling, was vitamien D vlakke van hierdie populasie steeds baie laag. Daar kan voorgestel word dat die huidige aanbeveling vir sonblootstelling verdubbel word om voldoende vitamien D status te bewerkstellig. Klein ortopediese chirurgiese ingrepe beinvloed nie sonblootstelling, vitamien D inname en dus vitamien D status post-operatief negatief nie. Hierdie pasiënte kan as ‘n "risiko" groep oorweeg word as gevolg van hul gemiddelde LMI klassifisering as vetsugtig en elektiewe ortopediese chirurgie wat aangedui is.

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