Quadriceps Muscle Strength Correlates With Serum Vitamin D and Knee Pain in Knee Osteoarthritis

A Diagnosis of Vitamin D Deficiency Is Associated With Increased Rates of Primary Patellar Instability and Need for Recurrent Surgical Stabilization

BACKGROUND

Vitamin D has been proven experimentally to affect musculoskeletal health. The purpose of this study was to identify the relationship between vitamin D deficiency and patellar instability.

HYPOTHESIS

Vitamin D deficiency is associated with an increased risk of experiencing primary patellar instability and recurrent patellar dislocation after primary surgical stabilization.

STUDY DESIGN

Retrospective comparative study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A 1:1 matched retrospective study of 328,011 patients diagnosed with vitamin D deficiency was performed using the PearlDiver database. Incidence of primary patellar instability was calculated according to sex and age. Rates of primary patellar instability and surgical stabilization for recurrent dislocation were calculated with sex- and age-specific stratifications. Multivariable logistic regression was used to compare the rates of primary injury and recurrent stabilization while controlling for demographics and medical comorbidities.

RESULTS

A total of 656,022 patients were analyzed. The overall 1-year incidence rate of patellar instability in patients with vitamin D deficiency was 82.6 per 100,000 person-years (95% CI, 73.2-92.9), compared with 48.5 (95% CI, 41.4-56.5) in the matched control. Women were significantly more likely to experience primary patellar instability within 1 (adjusted odds ratio [aOR] = 1.45; 95% CI, 1.12-1.88) and 2 years (aOR, 1.31; 95% CI, 1.07-1.59) of hypovitaminosis D diagnosis. Patients aged 10 to 25 years with hypovitaminosis D were at greater risk of requiring recurrent patellar stabilization for both men (aOR, 2.48; 95% CI, 1.06-5.80) and women (aOR, 1.77; 95% CI, 1.04-3.02).

CONCLUSION

Patients diagnosed with vitamin D deficiency experienced higher rates of primary patellar instability and have greater risk of requiring recurrent surgical stabilization for subsequent dislocations.

CLINICAL RELEVANCE

These results suggest that monitoring and proactively treating vitamin D deficiency in the physically active patient may lower the risk of suffering primary patellar instability or recurrence after surgical stabilization.

How Do Muscle Function and Quality Affect the Progression of KOA? A Narrative Review

Knee osteoarthritis (KOA) is widely recognized as a chronic joint disease characterized by degeneration of knee cartilage and subsequent bone hyperplasia. However, it is important to acknowledge the significant role of muscles in the development and progression of KOA. Muscle function (MF) and muscle quality (MQ) are key factors in understanding the involvement of muscles in KOA. Quantitative indices such as muscle mass, muscle strength, muscle cross-sectional area, muscle thickness, and muscle fatigue are crucial in assessing MF and MQ. Despite the growing interest in KOA, there is a scarcity of studies investigating the relationship between muscles and this condition. This review aims to examine the commonly used indices and measurement methods for assessing MF and MQ in clinical settings, while also exploring the association between muscles and KOA. Furthermore, this article highlights the importance of restoring MF and MQ to enhance symptom management and improve the quality of life for patients with KOA.

Serum vitamin D insufficiency is correlated with quadriceps neuromuscular functions in patients with anterior cruciate ligament injury: A preliminary study

Background

This study aimed to investigate the correlations of serum vitamin D insufficiency with quadriceps neuromuscular function in patients with anterior cruciate ligament (ACL) injury.

Methods

A cross-sectional study was conducted. Eighteen patients with a primary, unilateral ACL injury who had insufficient serum vitamin D concentrations (<30 ng/ml) were recruited for the study. Bilateral quadriceps neuromuscular function, including maximal strength, the speed of rapid contraction, and inhibition, were measured on an isokinetic dynamometer with the hip and the knee joint flexion at 90° and 45°, respectively. Quadriceps strength was measured by maximal voluntary isometric contractions (MVIC); the speed of rapid contraction was quantified by the rate of torque development (RTD), which was divided into the early (RTD0-50) and the late phase (RTD100-200); quadriceps inhibition was quantified by the central activation ratio (CAR). Serum vitamin D concentration was quantitatively determined by serum 25(OH)D concentration measured by the 25(OH)D ELISA kit. The Spearman rank correlation analysis was used to examine the correlation between the vitamin D concentration and bilateral quadriceps MVIC, RTD0-50, RTD100-200, and CAR, respectively.

Results

The results of Spearman rank correlation analyses showed that the serum 25(OH)D concentration was significantly correlated with bilateral quadriceps MVIC (injured: r = 0.574, p = 0.013; uninjured: r = 0.650, p = 0.003) and RTD0-50 (r = 0.651, p = 0.003), and CAR (r = 0.662, p = 0.003) on the uninjured limb. However, no significant correlations were found between the serum 25(OH)D concentration and the other outcomes.

Conclusions

The serum vitamin D concentration correlates with quadriceps neuromuscular function in patients with ACL injury who had vitamin D insufficiency.

A Diagnosis of Vitamin D Deficiency Is Associated With Increased Rates of Anterior Cruciate Ligament Tears and Reconstruction Failure

PURPOSE

To characterize the association between a diagnosis of hypovitaminosis D and primary anterior cruciate ligament (ACL) tear, primary anterior cruciate ligament reconstruction (ACLR), and revision ACLR in different sex and age cohorts.

METHODS

In this retrospective cohort study of the PearlDiver claims database, records were queried between January 1, 2011, and October 31, 2018 for all patients aged 10 to 59 years who received a diagnosis of hypovitaminosis D. Rates of primary ACL tears, primary reconstruction, and revision reconstruction were calculated for sex- and age-specific cohorts and compared with a control of patients without a diagnosis of hypovitaminosis D. Incidence rates for primary ACL injuries were calculated, and multivariable logistic regression was used to compare rates of ACL injury, primary reconstruction, and revision reconstruction while controlling for age, sex, Charlson Comorbidity Index, and several other comorbidities.

RESULTS

Among the 328,011 patients (mean age 41.9 ± 12.6 years, 65.8% female) included in both the hypovitaminosis D and control cohorts, the incidence of ACL tears was 115.2 per 100,000 person-years (95% confidence interval [CI] 107.2-123.7) compared with 61.0 (95% CI 55.2-67.2) in the demographic- and comorbidity-matched control cohort. The study cohort was significantly more likely to suffer an ACL tear over a 1- (aOR 1.67, 95% CI 1.41-1.99, P < .001) and 2-year (aOR 1.81, 95% CI 1.59-2.06, P < .001) period. This trend remained for both male patients at the 1- (aOR 1.66, 95% CI 1.29-2.14, P < .001) and 2-year (aOR 1.68, 95% CI 1.37-2.06, P < .001) mark and female patients at the 1- (aOR 1.69, 95% CI 1.33-2.14, P < .001) and 2-year (aOR 1.80, 95% CI 1.51-2.14, P < .001) mark. Finally, patients with vitamin D deficiency had a significantly increased likelihood of undergoing a revision ACLR within 2 years of a primary reconstruction (aOR 1.28, 95% CI 1.05-1.55, P = .012).

CONCLUSIONS

This study reports an association between patients previously diagnosed with hypovitaminosis D and significantly increased rates of both index ACL tears (81% increase within 2 years of diagnosis) and revision ACLR (28% within 2 years). These results identify a population with increased odds of injury and provide valuable knowledge as we expand our understanding of the relationship between vitamin D and musculoskeletal health.

LEVEL OF EVIDENCE

Level III, retrospective database study.

Relationship between 25-hydroxy vitamin D and knee osteoarthritis: a systematic review and meta-analysis of randomized controlled trials

Objective

In order to examine the relationship between 25-hydroxyl vitamin D and knee osteoarthritis (KOA), a meta-analysis of 8 randomized controlled trials (RCTs) publications was hereby performed.

Methods

For the purpose of finding pertinent research, the databases of PubMed, Embase and the Cochrane Library were searched. Factors including tibial cartilage volume, joint space width (JSW), synovial fluid volume, and Western Ontario and McMaster Universities Arthritis Index (WOMAC) were correspondingly evaluated, and the results were expressed using SMD and 95% confidence intervals (CI).

Results

The present meta-analysis evaluated the effects of vitamin D supplementation in patients with knee osteoarthritis, with 3,077 patients included. The results showed that vitamin D administration had a statistically significant impact on the amount of synovial fluid, Visual Analog Scale (VAS) and tibial cartilage. The pain and function scales of the WOMAC scale presented a statistically significant difference, and there was no discernible difference between the vitamin D and placebo groups in the stiffness scale. Additionally, bone marrow lesions and alterations in the diameter of the joint space were not influenced by the administration of vitamin D, and according to a subgroup study, a daily vitamin D supplement containing more than 2,000 IU significantly slowed the development of synovial tissue.

Conclusion

Vitamin D supplementation did benefit those suffering from knee discomfort and knee dysfunction.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022332033, identifier: CRD42022332033.

The Role of Vitamin D in the Development and Progression of Osteoarthritis

"Low levels of vitamin D in patients with osteoarthritis (ΟΑ) rather adversely affect the structure and function of articular cartilage. Low levels of vitamin D are also associated with joint pain, limited physical activity, quality of life, as well as decreased muscle strength, primarily in the lower extremities with adverse OA progression. A high percentage of low vitamin D levels was found in patients with OA and joint arthroplasty as well as a less satisfactory postoperative follow-up in patients with low vitamin D levels. The administration of vitamin D supplementation in patients with knee osteoarthritis has been associated with improved articular cartilage architecture, and reduced joint pain, combined with improved functionality and quality of life in patients with OA. "

Association of Serum Vitamin D with Serum Cytokine Profile in Patients with Knee Osteoarthritis

OBJECTIVE

The role of vitamin D in the pathogenesis of osteoarthritis (OA) is not well understood. In this study, we aimed to investigate the association of serum vitamin D with the serum cytokine profile in patients with primary knee OA.

DESIGN

In a cross-sectional study, 116 patients with radiologic diagnosis of grade I to III knee OA were included. The study population included 79 (75.9%) females and 25 (24.1%) males with a mean age of 55.1 ± 9.6 years. The serum concentration of IL-6, IL-8, TNF-α, IL-4, IL-10, IL-13, and vitamin D were assessed using an enzyme-linked immunosorbent assay. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was used for the assessment of patient's reported disability associated with knee OA.

RESULTS

Serum vitamin D status was deficient, insufficient, and sufficient in 18 (15.5%), 63 (54.3%), 35 (30.2%) patients, respectively. Higher levels of serum IL-6 were observed in patients with vitamin D deficiency (P = 0.022). The mean serum vitamin D level was not associated with OA grade (P = 0.88) and WOMAC scores of the patients (P = 0.67). Serum IL-6 level was significantly associated with both OA grade and WOMAC scores of the patients (P < 0.001 and P = 0.001, respectively). The vitamin D status was not significantly associated with the serum levels of other evaluated cytokines.

CONCLUSION

Vitamin D deficiency in knee OA seems to be associated with a higher release of IL-6. Therefore, vitamin D supplementation could reduce the disease burden by controlling the IL-6 release.

The Role of Vitamin D in Early Knee Osteoarthritis and Its Relationship with Their Physical and Psychological Status

Osteoarthritis (OA) is a common joint condition and one of the greatest causes of disability worldwide. The role of vitamin D in the origin and development of the disease is not clear, although it could have important implications for diagnosis and treatment. For this proposal, a cross-sectional study with a non-probabilistic sample was performed. In total, 48 with early osteoarthritis (EOA) and 48 matched controls were selected, and serum 25(OH)D and parathyroid hormone (PTH) levels were analyzed. In addition, physical and psychological variables were measured to establish their relationship with vitamin D levels. Patients with EOA showed lower levels (22.3 ± 7.3 ng/mL) in comparison to matched controls (29.31 ± 9.2 ng/mL). A statistically significant higher number (Chi-squared = 8.525; p = 0.004) of patients with EOA had deficiency levels (<20 ng/mL) compared to the control group. Patients with lower vitamin D levels showed higher levels of pain intensity, disability, and anxiety, as well as poorer values for sit-to-stand, walking speed, and social participation. Correlation analysis showed a relationship between serum 25(OH)D, PTH and pain intensity, and social participation. These results highlight the relevance of vitamin D in the early diagnosis and prevention of EOA.

Acute effect of kinesiology taping on muscle strength, tissue temperature, balance, and mobility in female patients with osteoarthritis of the knee

AIM

The data on the action mechanism of the kinesiology taping (KT) used to reduce pain and inflammation, provide mechanical support, and facilitate or inhibit muscles in the treatment of osteoarthritis (OA) of the knee are contradictory. The aim of this study was to investigate the acute effects of KT treatment on muscle strength, tissue temperature, balance, and mobility in female patients diagnosed with OA of the knee.

METHODS

Thirty-four female patients (age: 60.26 ± 6.51 years) who were diagnosed with Kellgren-Lawrence Grade 2 OA according to the American Rheumatology Association (ACR-1986) criteria were included in the study. Patients who were performed KT with the superior Y, inferior Y, and U strip techniques were evaluated before and 30 min after taping. Muscle strength was assessed with a handheld dynamometer, tissue temperature with a thermal camera, balance with a monoaxial balance platform, and mobility the Timed Up and Go (TUG) test.

RESULTS

After taping, there was a significant increase in the muscle strength during both extension and flexion (p<.001, p=.005). There was no statistically significant difference in the tissue temperature and balance scores before and after taping (p=.219, p>.05). There was a significant improvement in TUG scores, which evaluated mobility, after taping (p=.033).

CONCLUSIONS

Although KT treatment seems to be ineffective on tissue temperature and balance in the short term in patients with OA of the knee, we are of the opinion that patients should be included in the treatment program due to its positive effects on muscle strength and mobility.

Is inflammatory signaling involved in disease-related muscle wasting? Evidence from osteoarthritis, chronic obstructive pulmonary disease and type II diabetes

Muscle loss is an important feature that occurs in multiple pathologies including osteoarthritis (OA), chronic obstructive pulmonary disease (COPD) and type II diabetes (T2D). Despite differences in pathogenesis and disease-related complications, there are reasons to believe that some fundamental underlying mechanisms are inherent to the muscle wasting process, irrespective of the pathology. Recent evidence shows that inflammation, either local or systemic, contributes to the modulation of muscle mass and/or muscle strength, via an altered molecular profile in muscle tissue. However, it remains ambiguous to which extent and via which mechanisms inflammatory signaling affects muscle mass in disease. Therefore, the objective of the present review is to discuss the role of inflammation on skeletal muscle anabolism, catabolism and functionality in three pathologies that are characterized by an eventual loss in muscle mass (and muscle strength), i.e. OA, COPD and T2D. In OA and COPD, most rodent models confirmed that systemic (COPD) or muscle (OA) inflammation directly induces muscle loss or muscle dysfunctionality. However, in a patient population, the association between inflammation and muscular maladaptations are more ambiguous. For example, in T2D patients, systemic inflammation is associated with muscle loss whereas in OA patients this link has not consistently been established. T2D rodent models revealed that increased levels of advanced glycation end-products (AGEs) and a decreased mTORC1 activation play a key role in muscle atrophy, but it remains to be elucidated whether AGEs and mTORC1 are interconnected and contribute to muscle loss in T2D patients. Generally, if any, associations between inflammation and muscle are mainly based on observational and cross-sectional data. There is definitely a need for longitudinal evidence through well-powered randomized control trials that take into account confounders such as age, disease-phenotypes, comorbidities, physical (in) activity etc. This will allow to improve our understanding of the complex interaction between inflammatory signaling and muscle mass loss and hence contribute to the development of therapeutic strategies to combat muscle wasting in these diseases.

The Relationship Between Daily Physical Activity and Pain in Individuals with Knee Osteoarthritis

Objective

Investigate the association between physical activity and pain severity in individuals with knee osteoarthritis.

Design

Cross-sectional; systematic review with meta-analyses.

Methods

Thirty-one participants with knee osteoarthritis underwent assessment of symptoms via self-report questionnaires and quantitative sensory testing. Following testing, physical activity and symptoms were monitored for seven days using accelerometers and logbooks. Cross-correlation analyses were performed on fluctuations in symptoms and physical activity across the week to detect the relative timing of the strongest association between pain and activity. These data were complemented by meta-analyses of studies that examined correlations between pain from knee osteoarthritis and physical activity or fitness.

Results

Pain severity at baseline correlated with moderate to vigorous physical activity (r2 = 0.161–0.212, P &lt; 0.05), whereby participants who were more physically active had less pain. Conversely, the peak of the cross-correlation analyses was most often positive and lagging, which indicated that pain was increased subsequent to periods of increased activity. These superficially discrepant findings were supported by the results of a meta-analysis of 13 studies and 9,363 participants, which identified significant heterogeneity for associations between physical activity and pain (I2 = 91%). Stronger inverse associations were found between fitness and pain.

Conclusions

Associations between physical activity and pain in people with knee osteoarthritis are variable and dynamic. These results reflect the beneficial impact of an active lifestyle and accompanying higher fitness. Yet, the side effect of acute periods of physical activity to transiently exacerbate pain may influence the behavior of some people to avoid activity because of pain.

Effects of kinesiotape on pain, range of motion, and functional status in patients with osteoarthritis: a randomized controlled trial

This study aimed to determine the effects of kinesiotape (KT) on pain, range of motion, and functional status in patients with osteoarthritis of the knee. In this randomized controlled trial, patients with knee osteoarthritis, based on American College of Rheumatology criteria, and Kellgren-Lawrence grade 2 or 3 criteria were selected. Visual analogue scale and active range of motion were the primary outcome measures. Timed Up and Go test and 6-min walk test, were the secondary outcome measures. Evaluation was performed at baseline (T0), after 1 hr (T1), and after 72 hr (T2). We recruited 27 patients with osteoarthritis (age, 57.33±8.72 years; 63% female; body mass index, 29.7±4.3 kg/m²) who were randomly assigned into KT or sham-KT groups. There was a significant group by time interaction for the visual analogue scale (P< 0.001, η²=0.593), active range of motion (flexion) (P<0.001, η²=0.492), active range of motion (extension) (P<0.001, η²=0.351), 6-min walk test (P<0.001, η²=0.568), and Timed Up and Go test (P=0.026, η²=0.136). Between-group comparisons revealed significant differences between KT and sham-KT in visual analogue scale and Timed Up and Go test in T1 and T2 assessments, with changes in knee flexion (P<0.002) and extension active range of motion (P<0.010) and 6-min walk test (P<0.044) at 72-hr posttreatment. This study showed that, 1 hr of KT is an effective treatment for decreasing pain and improving active range of motion and physical function at a 72-hr follow-up in patients with osteoarthritis.

Therapeutic and Preventive Potential of Vitamin D Supplementation in Knee Osteoarthritis

Objective

Vitamin D deficiency is linked with pain, function, and radiographic progression of knee osteoarthritis (KOA), but the results of studies addressing the association and effect of vitamin D supplementation for pain, function, quality of life, radiographic disease, and progression are inconsistent. The aim of this review is to determine the therapeutic and preventive potential of vitamin D supplementation in KOA.

Method

Eligible pertinent English language studies published in 2000 and thereafter in Medline/PubMed, Scopus, and Google Scholar were selected by using keywords that include “knee osteoarthritis,” “vitamin D supplementation,” “pain,” “structural abnormalities,” “treatment,” and “progression.”

Results

The results of a few studies showed a preventive potential for vitamin D in KOA, but most of the randomized clinical trials that assessed the therapeutic efficacy of vitamin D supplementation in KOA found no clear therapeutic effect, with the exception of one study that found a small but significant effect of vitamin D on pain and knee function. Nonetheless, the results of a few longitudinal studies as well as systematic reviews are promising and thus encourage further studies. Inconsistent results on the effect of vitamin D on KOA may be attributed to factors such as severity of KOA, baseline level of serum vitamin D, duration of treatment, and vitamin D dosages.

Conclusion

Given the multiple skeletal and extraskeletal benefits of vitamin D supplementation in elderly people, the issue of vitamin D supplementation in KOA requires further study to elucidate the dosage and duration of treatment that provides the most effective therapeutic effect.

Correcting Vitamin D Insufficiency Improves Some But Not All Aspects of Physical Performance During Winter Training in Taekwondo Athletes

We investigated the effects of vitamin D₃ supplementation on physical performance during winter training in vitamin D insufficient taekwondo athletes. Thirty-five collegiate male and female taekwondo athletes, aged 19-22 years with low serum 25(OH)D concentration (28.8 ± 1.10 nmol/L), were randomly assigned to a vitamin D group (n = 20) or a placebo group (n = 15). Subjects received either a vitamin D₃ capsule (5,000 IU/day) or a placebo during 4 weeks of winter training. Blood samples were collected for analyzing serum 25(OH)D concentration. Physical performance tests included Wingate anaerobic test, isokinetic muscle strength and endurance, a countermovement jump test, sit-ups, agility test, and 20-m pacer. Serum 25(OH)D concentrations increased significantly in the vitamin D group (96.0 ± 3.77 nmol/L) after 4 weeks of supplementation, but no changes were found in the placebo group (F = 242.44, p = .000). There were significant interaction effects for anaerobic peak power (F = 7.49, p = .010) and isokinetic knee extension at 180 deg/s (F = 6.08, p = .019). Changes in serum 25(OH)D concentration were positively associated with changes in peak power and isokinetic knee extension at 180 deg/s. However, no significant interaction effects were observed in other performance variables. This study suggests that 4 weeks of vitamin D supplementation elevates serum 25(OH)D concentration to sufficient levels. Correcting vitamin D insufficiency improves some but not all aspects of performance. Thus, efficacy of vitamin D supplementation to enhance performance remains unclear.

Dehydroepiandrosterone: Molecular mechanisms and therapeutic implications in osteoarthritis

Dehydroepiandrosterone (DHEA), a 19-carbon steroid hormone primarily synthesized in the adrenal gland, exerts a chondroprotective effect against osteoarthritis (OA) and has been considered an effective candidate of disease-modifying OA drugs (DMOADs) that slow disease progression. We and others previously demonstrated that DHEA exerted a beneficial effect on osteoarthritic cartilage by positively modulating the balance between anabolic and catabolic factors (e.g., MMPs/TIMP-1, ADAMTS/TIMP-3 and cysteine proteinases/cystatin C), inhibiting catabolic signaling pathways (e.g., Wnt/β-catenin), and suppressing proinflammatory cytokines-mediated low-grade synovial inflammation (e.g., IL-1β). However, the full picture of the pharmacological molecular mechanism(s) underlying the activity of DHEA against OA is still incomplete, and a comprehensive and up-to-date review article in this field is unavailable. In this review, recent findings (apart from the well documented pathogenesis of OA) regarding disease-related mechanisms involving low grade synovial inflammation, cartilage matrix stiffness, chondrocyte autophagy and the roles of a variety of catabolic cellular signaling pathways are discussed. Moreover, the possible relationship between these disease-related mechanisms and DHEA action is discussed. Emerging evidence from in vivo and in vitro studies were scrutinized and are concisely presented to demonstrate the investigational and putative mechanisms underlying the anti-OA potential of DHEA.

The role of quadriceps muscle strength in the development of falls in the elderly people, a cross-sectional study

Background

Falls are a major health issue in the elderly people and an important cause of bone fracture. The aim of this study was to determine the association between quadriceps muscle strength (QMS) and falls in the elderly subjects.

Methods

All eligible participants of the Amirkola Cohort Study entered the study. Data regarding demographic characteristics, clinical and laboratory examinations were provided between 2011 to 2014. Occurrence of falls during previous year was determined by interview and review of the medical records. The study patients were divided into low, moderate and high muscle strength groups according to QMS values ≥ 30, 15-30, and < 15 kg respectively). Association between muscle strength and falls was determined by using multiple logistic regression analysis with calculation of odds ratio (OR).

Results

A total 1028 participants (females, 44.3%) were analyzed and 178(17.3%) subjects experienced a fall. Individuals with falls had higher age (p = 0.001) and lower QMS value (p = 0.001). After adjustment for all clinical and demographic variables, occurrence of falls was negatively associated with QMS and positively associated with age > 70 years old. Compared to group with QMS ≥ 30 kg, the prevalence of falls in low and moderate QMS groups increased by OR = 3(95% CI, 1.78-5.05) and 2.18 (95% CI, 1.22-3.42) respectively.

Conclusion

These findings indicate that older subjects with lower QMS are at greater risk of falls. These findings provide a rational for muscle strengthening exercise in older people.

High Prevalence of Vitamin D Deficiency among Iranian Population: A Systematic Review and Meta-Analysis

BACKGROUND

The prevention and correction of vitamin D deficiency requires a precise depiction of the current situation and identification of risk factors in each region. The present study attempted to determine these entities using a systematic review and meta-analysis in Iran.

METHODS

Articles published online in Persian and English between 2000 and November 1, 2016, were reviewed. This was carried out using national databases such as SID, IranMedex, Magiran, and IranDoc and international databases such as PubMed, Google Scholar, and Scopus. The heterogeneity index among the studies was determined using the Cochran (Q) and I² test. Based on the heterogeneity results, the random-effect model was applied to estimate the prevalence of vitamin D deficiency. In addition, meta-regression analysis was used to determine heterogeneity-suspected factors, and the Egger test was applied to identify publication bias.

RESULTS

The meta-analysis of 48 studies identified 18531 individuals with vitamin D deficiency. According to the random-effect model, the prevalence of vitamin D deficiency among male, female, and pregnant women was estimated to be 45.64% (95% CI: 29.63 to 61.65), 61.90% (95% CI: 48.85 to 74.96), and 60.45% (95% CI: 23.73 to 97.16), respectively. The results of the meta-regression analysis indicated that the prevalence of vitamin D deficiency was significantly different in various geographical regions (β=4.4; P=0.023).

CONCLUSION

The results obtained showed a significant prevalence of vitamin D deficiency among the Iranian population, a condition to be addressed by appropriate planning.