Prevalence of vitamin D deficiency and its correlates: results of a community-based study conducted in Karachi, Pakistan Aysha Habib Khan, Romaina Iqbal, Ghazala Naureen, Farhan Javed Dar & Feroza Nazir Ahmed Archives of Osteoporosis ISSN 1862-3522 Arch Osteoporos DOI 10.1007/s11657-012-0108-x
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Author's personal copy Arch Osteoporos DOI 10.1007/s11657-012-0108-x
ORIGINAL ARTICLE
Prevalence of vitamin D deficiency and its correlates: results of a community-based study conducted in Karachi, Pakistan Aysha Habib Khan & Romaina Iqbal & Ghazala Naureen & Farhan Javed Dar & Feroza Nazir Ahmed
Received: 4 October 2012 / Accepted: 16 October 2012 # International Osteoporosis Foundation and National Osteoporosis Foundation 2012
Abstract Summary Of the 305 premenopausal females in a crosssectional study in randomly selected communities of Karachi, Pakistan, 90.1 % showed to be vitamin D deficient. Age, town of residence, and housing structure were significant predictors of vitamin D levels. Measures to address D deficiency and its associated long latency effects are urgently needed. Aims This study aims to find out the prevalence and risk factors of vitamin D deficiency in community-dwelling premenopausal females in Karachi. Methods A cross-sectional study was conducted in randomly selected communities downtown (Saddar) and suburbs (Gulshan and Malir Town) in Karachi, Pakistan. Information related to sociodemographics (age, education, employment, and household income), housing structure, sunlight exposure, and skin pigmentation as well as dietary intake (using a food frequency questionnaire) was collected. Serum vitamins D3 levels were also measured. Mean and SD was computed for continuous variables and frequency and proportions were computed for categorical variables. Data were further analyzed by Chi-square test and ANOVA. Multiple
linear regression analysis was done to find out determinants of vitamin D (VD) levels. Results Total of 305 premenopausal females were recruited. Mean age, BMI, and waist circumference of the study participants was 31.97±8 years, 25.06±5.6 kg/m2, and 88.42± 13.3 cm, respectively. Majority of the females were vitamin D deficient (91.50 %) with mean vitamin D levels of 21.77± 21.66 nm/L. Mean vitamin D levels were significantly different among females residing in downtown and suburbs. High frequency of vitamin D deficiency was observed in females dwelling in downtown (Saddar). According to the results of multiple linear regression analysis, determinants of VD levels were age, town of residence, and housing structure. Conclusion High prevalence of vitamin D deficiency is seen in females in the community of Karachi, Pakistan. Age, town of residence, and housing structure were the significant predictors of vitamin D levels. Measures to combat the issue of D deficiency and its associated long latency effects are urgently needed. Keywords Vitamin D deficiency (VDD) . Risk factors . Community . Karachi . Pakistan
Both Aysha Habib Khan and Romaina Iqbal contributed equally to this study. A. H. Khan (*) Department of Pathology and Microbiology and Medicine, Aga Khan University, Stadium Road, Karachi 74800, Pakistan e-mail:
[email protected] R. Iqbal Department of Community Health Sciences and Medicine, Aga Khan University, Karachi, Pakistan G. Naureen : F. J. Dar : F. N. Ahmed Department of Pathology and Microbiology, Aga Khan University, Karachi, Pakistan
Introduction A large population group of immigrant Pakistanis living in Europe has been identified to be at major risk of vitamin D deficiency (VDD) due to low vitamin D (VD) intake and insufficient sun exposure [1]. Studies have also highlighted more severe VDD in Pakistanis when compared with similar other immigrant born in Sri Lanka, Turkey, Iran, Somalia, Vietnam, Somalia, and Norway [2–5]. However, it was presumed that in Pakistan, being a sundrenched country of the world, VDD would not be a problem in subjects residing there. Though, data from Pakistan had been sparse; but during the last 3 years, reports from
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Pakistan had shown a high prevalence of VDD in ambulatory care [6, 7]. Although the best characterized effects of VDD and insufficiency are associated with musculoskeletal system, its association with many chronic diseases is substantial in recent literature; Pakistan is a leading affecter in many of these chronic diseases; for example, cardiovascular diseases, diabetes, and cancer are among the top ten causes of morbidity and mortality and account for approximately 25 % of total deaths [8]. For TB, it is 1 of the 22 countries listed by the World Health Organization as having a high incidence of TB [8]. Evidence indicates that intake of VD via supplementation or lifestyle measures are associated with reduced incidence of fractures, many cancers, and the risk of cardiovascular disease and stroke. Despite high prevalence of VDD in our region, however, no community-based study has been carried out so far to elucidate the role of various risk factors in the development/prevention of VDD in adult Pakistani population. This study was undertaken to find out the prevalence and risk factors of VDD in community-dwelling premenopausal females in Karachi.
Khan University Hospital (AKUH) clinical laboratory phlebotomy center in the selected towns. Selection was done in a systematic way with a random start. In case of apartments, every third apartment was included. If the household member did not agree to participate then the next house was offered participation followed by selection of the third house from the previous one. Subject selection
Material and methods
One premenopausal female ≥18 years of age satisfying the inclusion criteria was invited to participate in the study from each household. The selected participants were apparently healthy with no signs and symptoms of VDD. In case of more than one eligible woman, one participant was randomly selected. Pregnant subjects; lactating mothers; patients previously treated for rickets and osteomalacia; on vitamin D supplementation (patients on following multivitamin preparations: Optilets M, Supradyn N, Centrum, Calci-D, Ossopan, Chewcal); on anti-epileptics, steroids, hormone replacement therapy; on bisphosphonates; on oral contraceptives; and recent fractures up to 1 year back were not recruited. Written informed consent was obtained from all participants.
Study design
Data collection
A cross-sectional community-based study was designed to assess the risk factors of vitamin D deficiency in premenopausal females in Karachi. The study was approved by Ethics Committee of Aga Khan University.
Recruitment of participants was initiated from downtown in January 2011 and continued till May 2011. Information related to sociodemographic and anthropometric details: age, weight, height, ethnicity, housing structure, duration of sun exposure and purdah observation, and skin tone were recorded. Information regarding housing structure included type of residence (apartment, town house, and small and large bungalows), number of rooms, and means of availability of sunlight in the house (presence of corridor/courtyard/ lawn/terrace). Dietary intake per day of the participants was recorded by using validated food frequency questionnaire (FFQ) through face to face interviews. For sunlight exposure assessment, data were recorded by validated questionnaire previously developed in a study conducted at AKU.
Selection of town from Karachi Karachi is the largest city and the main seaport and financial center of Pakistan. Its estimated population is between 13 and 15 million. The city is spread over 3,527 km2 (1,362 square miles) in area. The city of Karachi is composed of 18 towns. Selection of towns was done by random draw from 18 towns. Three towns were picked; of which one was downtown (Saddar) and the other two towns were suburb (Gulshan-e-Iqbal and Malir). There are several ethnic groups living in all three towns including Muhajirs, Punjabis, Sindhis, Kashmiris, Pakhtoons, Memons, Gujarati, Ismailis, etc. Over 99 % of the population are Muslims. Town houses, apartments, and small and large bungalows are prominent types of residence in the locality. Selection of household Household selection was done by recruitment of participants from lanes adjacent and across the starting point at Aga
Sampling Venous blood was drawn in the fasting state between 8:00 to 10:00 am and placed in plain vacutainer at AKUH clinical laboratory phlebotomy center of the respective towns. Five milliliters of blood sample was taken for analysis of serum levels of vitamin D (25(OH)D). Samples from the phlebotomy center were transported in ice to the main laboratory of AKUH within 2 h of sampling. The serum was separated after centrifugation of blood samples, aliquot, and analyzed.
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Biochemical analysis Serum 25(OH)D concentration was measured by electrochemiluminescence immunoassay on Elecsys auto analyzer (Roche Diagnostics, USA). For quality control, low, medium, and high ElecsysPreciControls were used. The withinrun CVs were 5.7, 5.7, and 5.4 % at concentrations of 25.2, 39.9, and 65.6 ng/mL. 25(OH)D3 blood levels were taken as: >75 nm/L (>30 ng/ml)-sufficient, 50–75 nm/L (21–29 ng/ml)insufficient, and
