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Low BMD among teaching doctors in India - July 2010

Study of bone mineral density in resident doctors working at a teaching hospital

available as non-PDF at http://www.jpgmonline.com/article.asp?issn=0022-3859;year=2010;volume=56;issue=2;spage=65;epage=70;aulast=Multani

The article claims that vitamin D was not associated with BMD, but claim was based on a decision point of 20ng/ml

Look at the data - it appears that 15 ng/ml would have been much better decision point


The following is just a portion of what is available on-line

SK Multani, V Sarathi, V Shivane, TR Bandgar, PS Menon, NS Shah
Department of Endocrinology, KEM Hospital, Seth G. S. Medical College, Parel, Mumbai-400 012, India

Date of Submission29-Mar-2009
Date of Decision31-Jul-2009
Date of Acceptance04-Dec-2009
Date of Web Publication8-Jul-2010

Correspondence Address:
V Sarathi
Department of Endocrinology, KEM Hospital, Seth G. S. Medical College, Parel, Mumbai-400 012 India
Source of Support:None, Conflict of Interest:None
DOI: 10.4103/0022-3859.65272

Context: The erratic lifestyle of resident doctors may affect their serum 25-hydroxy yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-0">yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-0">vitaminD 25-(OH)D levels and bone mineral density (BMD). Aim: To study BMD and the effect of environmental factors on it in resident doctors. Settings and Design: Prospective, cross-sectional study conducted in a tertiary healthcare centre. Materials and Methods: BMD was obtained by dual-energy X-ray absorptiometry and was correlated with various factors including weight, height, body mass index (BMI), sun exposure, physical activity, parathyroid hormone, 25-(OH)D, dietary factors. Statistical Analysis: SPSS software Version 10 (Unpaired t test was used to compare BMD of different groups and Pearson's correlation coefficient was used to calculate correlation). Results: Two hundred and fourteen apparently healthy resident doctors were enrolled in the study. Based on Caucasian normative data, osteopenia was noted in 104 (59.7%) males and 27 (67.5%) females. Thirty-two (18.39%) males and five (12.5%) females had osteoporosis. The BMD values of males were 0.947±0.086, 0.911±0.129 and 1.016±0.133 at lumbar spine, femur neck and total hip while those in females were 0.981±0.092, 0.850±0.101 and 0.957±0.103 respectively. BMD of our cohort was lesser by 12.5-18.2% and 4.2-14.5% than the Caucasian and available Indian figures, respectively. BMD had significant positive correlation with weight, height, BMI, physical activity, and dietary calcium phosphorus ratio. 25-(OH)D levels were insufficient in 175 (87.5%) subjects but had no correlation with BMD. Conclusions: Young healthy resident doctors had significantly lower BMD, contributors being lower BMI, lower height, reduced bioavailability of dietary calcium and inadequate physical activity. Deficiency of yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-1">yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-1">vitaminD did not contribute to low BMD.

The risk of osteoporosis and hence osteoporotic fractures is related to peak bone mass (PBM) achieved.[http://www.jpgmonline.com/article.asp?issn=0022-3859;year=2010;volume=56;issue=2;spage=65;epage=70;aulast=Multani#ref1|1]The precise age at which PBM is achieved is still controversial. Two recent Indian studies report PBM to be achieved at an average age of 26-30 years.http://www.jpgmonline.com/article.asp?issn=0022-3859;year=2010;volume=56;issue=2;spage=65;epage=70;aulast=Multani#ref],[http://www.jpgmonline.com/article.asp?issn=0022-3859;year=2010;volume=56;issue=2;spage=65;epage=70;aulast=Multani#ref3|Several factors prevent realization of PBM. Genetic factors account for up to 85% of the variation in bone mass, while environmental factors such as calcium and yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-2">yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-2">vitaminD deficiency, poor physical activity and poor sunlight exposure account for the rest.

Due to hectic and erratic work schedules, resident doctors are more likely to have poor sun exposure and unhealthy dietary habits. They are also likely to have inadequate physical activity owing to their sedentary lifestyle. These factors may affect their yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-3">yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-3">vitaminD status and bone mineral density (BMD). Hence, we undertook a study to determine the BMD and effect of anthropometric parameters, sunlight exposure, physical activity, dietary factors including protein, calcium, and phosphorus intake, and yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-4">yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-4">vitaminD status on it in resident doctors at a tertiary teaching hospital in Mumbai.

Materials and Methods| |Top
This prospective, cross-sectional study was carried out between May and August 2003 after obtaining the approval of the institutional ethics committee. The research participants were enrolled after obtaining a written informed consent.
Pregnant and lactating women, those with medical disorders that are likely to affect BMD, those who had received steroids, antitubercular or antiepileptic medication within the last two years, those who had fractures within the last two years and those who were on calcium and yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-5">yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-5">vitaminD supplements for the last three months were excluded from the study. All subjects were asked for history of smoking (number of cigarettes per week), alcohol consumption (g/d) and history of osteoporosis or non-traumatic fractures in the family. Dietary intake of calcium, phosphorus, calories and protein from all dietary sources was evaluated by 24-h dietary recall. Calculations were based on published food tables detailing the nutritive value of Indian foods.[http://www.jpgmonline.com/article.asp?issn=0022-3859;year=2010;volume=56;issue=2;spage=65;epage=70;aulast=Multani#ref55]Desired dietary calcium to protein ratio was taken as 16 to 20:1 (mg:g) for optimal utilization of dietary calcium,[http://www.jpgmonline.com/article.asp?issn=0022-3859;year=2010;volume=56;issue=2;spage=65;epage=70;aulast=Multani#ref66]while desired dietary calcium to phosphorus ratio was taken as 1:1 for better bioavailability of calcium.[http://www.jpgmonline.com/article.asp?issn=0022-3859;year=2010;volume=56;issue=2;spage=65;epage=70;aulast=Multani#ref77]
Participation in various physical activities since the time of admission in the medical college was recorded. It was assessed using the Global Physical Activity Questionnaire (GPAQ) developed by WHO ( www.who.int/chp/steps) and expressed as minutes/week.
Total sunlight exposure to the face and the hands (around mid-arm downwards) per day between 8.00 am and 5.00 pm in summer and between 9.00 am and 3.00 pm in winter was calculated by using a questionnaire.[http://www.jpgmonline.com/article.asp?issn=0022-3859;year=2010;volume=56;issue=2;spage=65;epage=70;aulast=Multani#ref88]Use of sunscreens was noted. Sun index was calculated as the product of hours of sun exposure per week and fraction of body surface area exposed to sunlight. Current sunlight exposure was calculated as exposure in one year prior to enrolment in study.
Blood was sampled between 8.00 am and 10.00 am in fasting state for determination of hemoglobin, serum calcium, phosphorus, alkaline phosphatase, albumin, creatinine, 25-hydroxy yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-6">yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-6">vitaminD (25-(OH)D) and intact parathyroid hormone (iPTH) levels. Samples were stored at -20?C until assayed. Serum calcium, phosphorus, albumin, creatinine, and alkaline phosphatase were measured by semiautoanalyzer. Serum 25-(OH)D was measured by radioimmunoassay (BioSource, Europe S.A., KIPI 1961, Belgium) with intra and inter-assay coefficients of variations of 3.85% and 6.49% respectively. Since there is no available normative data for Indians, subjects with 25-(OH)D concentration ?20 ng/ml were considered as yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-7">yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-7">vitaminD sufficient and <20ng/ml as insufficient, in this study. Serum iPTH was estimated by two-site binding Immunoradiometric assay (Diagnostic Systems Laboratories (DSL-8001), Webster, Texas, USA.). High iPTH values were defined as >55 pg/ml (upper limit of normal for assay kit). The intra- and inter-assay coefficient of variations was 2% and 3.92% for iPTH respectively.
Bone mineral density was assessed at lumbar spine and proximal femur by dual-energy X-ray absorptiometry DXA using Hologic inc. USA model Delphi W 70460. The short-term in vivo precision (coefficient of variation %) in our unit was as follows; lumbar spine: 1.09%, femoral neck: 3.29% and total hip: 1.26%. Bone mineral density was expressed as g/cm2as well as T scores and Z scores using Caucasian normative data. Osteopenia and osteoporosis were defined as per recommendations of The International Society for Clinical Densitometry.9]Absolute BMD of our study population was also compared with previously available Indian data.[http://www.jpgmonline.com/article.asp?issn=0022-3859;year=2010;volume=56;issue=2;spage=65;epage=70;aulast=Multani#ref1010]
Statistical analysis was done using SPSS Version 10. Continuous variables were expressed as mean±SD. Correlations between BMD and various factors were calculated by Pearson's correlation coefficient. Comparison of study population's BMD to that of Caucasian and available Indian data was done by using independent t test (P<0.05 was considered to be statistically significant). Power of the overall study is 90% while that for males and females is 90% and 80% respectively.
:: Results Top

Two hundred and fourteen (174 males and 40 females, M:F=4.35:1) resident doctors were enrolled in the study. The baseline characteristics of the study population are shown in [ja<x>vascript:omovimg('viewimaget.asp?img=jpgm_2010_56_2_65_65272_t1.jpg')|Table 1]. When compared to Caucasian normative database (Manufacturer's database), only 38 male and eight female resident doctors were found to have normal BMD at all sites. While rest had osteopenia or osteoporosis [ja<x>vascript:omovimg('viewimaget.asp?img=jpgm_2010_56_2_65_65272_t2.jpg')|Table 2]. Absolute BMD (g/cm2) at various sites is compared with Caucasian and previously available Indian data in [ja<x>vascript:omovimg('viewimaget.asp?img=jpgm_2010_56_2_65_65272_t3.jpg')|Table 3]and [ja<x>vascript:omovimg('viewimaget.asp?img=jpgm_2010_56_2_65_65272_t4.jpg')|Table 4]. The absolute BMD of resident doctors was lower than that of Caucasians and previously available Indian data at all measured sites. It was lesser by 12.5-18.2% in males and 13.5-17.3% in females than that of Caucasians and by 4.2-12.2% in males and 8.35-13.5% in females than that of available Indian data.

Bone mineral density of study population is correlated with various factors separately in male [ja<x>vascript:omovimg('viewimaget.asp?img=jpgm_2010_56_2_65_65272_t5.jpg')|Table 5]and female [ja<x>vascript:omovimg('viewimaget.asp?img=jpgm_2010_56_2_65_65272_t6.jpg')|Table 6]resident doctors. Weight and body mass index (BMI) had significant positive correlation with BMD of all measured sites in both groups. Height had significant positive correlation with BMD of all measured sites in males but not with BMD of any site in females. Age had no significant positive correlation with BMD of any site in either sex.

Sunlight exposure showed a decreasing trend over the years after entry into medical profession as seen in [ja<x>vascript:omovimg('viewimaget.asp?img=jpgm_2010_56_2_65_65272_f7.jpg')|Figure 1]. Current sunlight exposure/week was lower in both males and females as shown in [ja<x>vascript:omovimg('viewimaget.asp?img=jpgm_2010_56_2_65_65272_t1.jpg')|Table 1]. Current sunlight exposure had significant positive correlation with serum 25-(OH)D in males (r=0.18, P=0.02) as well as females (r=0.38, P=0.01) but not with BMD of any measured site in either group.
As shown in [ja<x>vascript:omovimg('viewimaget.asp?img=jpgm_2010_56_2_65_65272_t1.jpg')|Table 1], mean serum calcium (corrected), phosphorus, albumin, and creatinine were normal while mean serum 25-(OH)D was low in both males and females. yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-8">yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-8">VitaminD status of study population is shown in [ja<x>vascript:omovimg('viewimaget.asp?img=jpgm_2010_56_2_65_65272_f9.jpg')|Figure 3]. yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-9">yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-9">VitaminD insufficiency was found in 175 (87.5%) subjects when 20 ng/ml was used as the cutoff for defining yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-10">yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-10">vitaminD insufficiency. Among males 137 (85%) were yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-11">yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-11">vitaminD insufficient while 38 (97.5%) females had yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-12">yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-12">vitaminD insufficiency. No correlation was observed between yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-13">yer style="background-color: Yellow; color: black;" id="google-toolbar-hilite-13">vitaminD status and BMD at any site in either group.

Low BMD among teaching doctors in India - July 2010        
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