Populations at risk for severe or complicated influenza illness: systematic review and meta-analysis.


Abstract

Objective To evaluate risk factors for severe outcomes in patients with seasonal and pandemic influenza.

Design Systematic review.

Study selection Observational studies reporting on risk factor-outcome combinations of interest in participants with influenza. Outcomes included death, ventilator support, admission to hospital, admission to an intensive care unit, pneumonia, and composite outcomes.

Data sources Medline, Embase, CINAHL, Global Health, and the Cochrane Central Register of Controlled Trials to March 2011.

Risk of bias assessment Newcastle-Ottawa scale to assess the risk of bias. GRADE framework to evaluate the quality of evidence.

Results 63 537 articles were identified of which 234 with a total of 610 782 participants met the inclusion criteria. The evidence supporting risk factors for severe outcomes of influenza ranged from being limited to absent. This was particularly relevant for the relative lack of data for non-2009 H1N1 pandemics and for seasonal influenza studies. Limitations in the published literature included lack of power and lack of adjustment for confounders was widespread: adjusted risk estimates were provided for only 5% of risk factor-outcome comparisons in 39 of 260 (15%) studies. The level of evidence was low for “any risk factor” (odds ratio for mortality 2.77, 95% confidence interval 1.90 to 4.05 for pandemic influenza and 2.04, 1.74 to 2.39 for seasonal influenza), obesity (2.74, 1.56 to 4.80 and 30.1, 1.74 to 2.39), cardiovascular diseases (2.92, 1.76 to 4.86 and 1.97, 1.06 to 3.67), and neuromuscular disease (2.68, 1.91 to 3.75 and 3.21, 1.84 to 5.58). The level of evidence was very low for all other risk factors. Some well accepted risk factors such as pregnancy and belonging to an ethnic minority group could not be identified as risk factors. In contrast, women who were less than four weeks post partum had a significantly increased risk of death from pandemic influenza (4.43, 1.24 to 15.81).

Conclusion The level of evidence to support risk factors for influenza related complications is low and some well accepted risk factors, including pregnancy and ethnicity, could not be confirmed as risks. Rigorous and adequately powered studies are needed.

What is already known on this topic

  • Certain patient populations are thought to be at higher risk for developing complicated or severe influenza illness
  • These groups are prioritised for vaccination as well as for antiviral treatment
  • The quantity and quality of evidence on risk factors for developing complicated or severe influenza illness is limited
  • While some risk factors could be corroborated, evidence to support other, well established risk factors for severe outcomes could not be found

What this study adds

Source: BMJ

Ultrasonographically guided peripheral intravenous cannulation of children and adults: a systematic review and meta-analysis. .


Peripheral intravenous cannulation is procedurally challenging and painful. We perform a systematic review to evaluate ultrasonographic guidance as an aid to peripheral intravenous cannulation.

METHODS: We searched MEDLINE, Cochrane Central Register of Controlled Trials, EMBASE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Web of Science, ClinicalTrials.gov, and Google.ca. We included randomized trials evaluating ultrasonographically guided peripheral intravenous cannulation and reporting risk of peripheral intravenous cannulation failure, number of attempts, procedure time, or time from randomization to peripheral intravenous cannulation. We separately analyzed pediatric and adult data and emergency department (ED), ICU, and operating room data. Quality assessment used the Cochrane Risk of Bias Tool.
RESULTS: We identified 4,664 citations, assessed 403 full texts for eligibility, and included 9 trials. Five had low risk, 1 high risk, and 3 unclear risk of bias. A pediatric ED trial found that ultrasonography decreased mean difference (MD) in the number of attempts (MD -2.00; 95% confidence interval [CI] -2.73 to -1.27) and procedure time (MD -8.10 minutes; 95% CI -12.48 to -3.72 minutes). In an operating room pediatric trial, ultrasonography decreased risk of first-attempt failure (risk ratio 0.23; 95% CI 0.08 to 0.69), number of attempts (MD -1.50; 95% CI -2.52 to -0.48), and procedure time (MD -5.95; 95% CI -10.21 to -1.69). Meta-analysis of adult ED trials suggests that ultrasonography decreases the number of attempts (MD -0.43; 95% CI -0.81 to -0.05). Ultrasonography decreased risk of failure (risk ratio 0.47; 95% CI 0.26 to 0.87) in an adult ICU trial.
CONCLUSION: Ultrasonography may decrease peripheral intravenous cannulation attempts and procedure time in children in ED and operating room settings. Few outcomes reached statistical significance. Larger well-controlled trials are needed.

Source: Annals of Emergency Medicine.

 

Effectiveness of a bundled intervention of decolonization and prophylaxis to decrease Gram positive surgical site infections after cardiac or orthopedic surgery: systematic review and meta-analysis.


Abstract

Objective To evaluate studies assessing the effectiveness of a bundle of nasal decolonization and glycopeptide prophylaxis for preventing surgical site infections caused by Gram positive bacteria among patients undergoing cardiac operations or total joint replacement procedures.

Design Systematic review and meta-analysis.

Data sources PubMed (1995 to 2011), the Cochrane database of systematic reviews, CINAHL, Embase, and clinicaltrials.gov were searched to identify relevant studies. Pertinent journals and conference abstracts were hand searched. Study authors were contacted if more data were needed.

Eligibility criteria Randomized controlled trials, quasi-experimental studies, and cohort studies that assessed nasal decolonization or glycopeptide prophylaxis, or both, for preventing Gram positive surgical site infections compared with standard care.

Participants Patients undergoing cardiac operations or total joint replacement procedures.

Data extraction and study appraisal Two authors independently extracted data from each paper and a random effects model was used to obtain summary estimates. Risk of bias was assessed using the Downs and Black or the Cochrane scales. Heterogeneity was assessed using the Cochran Q and I2 statistics.

Results 39 studies were included. Pooled effects of 17 studies showed that nasal decolonization had a significantly protective effect against surgical site infections associated with Staphylococcus aureus (pooled relative risk 0.39, 95% confidence interval 0.31 to 0.50) when all patients underwent decolonization (0.40, 0.29 to 0.55) and when only S aureus carriers underwent decolonization (0.36, 0.22 to 0.57). Pooled effects of 15 prophylaxis studies showed that glycopeptide prophylaxis was significantly protective against surgical site infections related to methicillin (meticillin) resistant S aureus (MRSA) compared with prophylaxis using β lactam antibiotics (0.40, 0.20 to 0.80), and a non-significant risk factor for methicillin susceptible S aureus infections (1.47, 0.91 to 2.38). Seven studies assessed a bundle including decolonization and glycopeptide prophylaxis for only patients colonized with MRSA and found a significantly protective effect against surgical site infections with Gram positive bacteria (0.41, 0.30 to 0.56).

Conclusions Surgical programs that implement a bundled intervention including both nasal decolonization and glycopeptide prophylaxis for MRSA carriers may decrease rates of surgical site infections caused by S aureus or other Gram positive bacteria.

Discussion

Although multiple studies have assessed the efficacy of interventions to prevent surgical site infections caused by Gram positive bacteria, these interventions are not uniformly applied to surgical patients. Our results showed that nasal decolonization was associated with decreased rates of Gram positive surgical site infections andStaphylococcus aureus surgical site infections among patients undergoing cardiac or orthopedic surgical procedures. However, these results remained statistically significant for S aureus surgical site infections, though not all Gram positive surgical site infections, when the meta-analysis was limited to randomized controlled trials. Additionally, a bundle that included nasal decolonization and glycopeptide prophylaxis for patients who carried methicillin (meticillin) resistant S aureus (MRSA) was associated with significantly decreased rates of surgical site infections caused by Gram positive bacteria and by S aureus.

We also found that routine use of prophylactic glycopeptides protected against MRSA infections but not against all Gram positive surgical site infections. Additionally, dual prophylaxis with a glycopeptide and another antimicrobial agent seemed to be more protective against Gram positive surgical site infections than prophylaxis with glycopeptides alone. This finding is consistent with studies of methicillin susceptible S aureus (MSSA) bacteremia, which found that vancomycin is less effective than a β lactam antibiotic for treating MSSA infections.63 64 These results are similar to the conclusions of a recent review article, which stated that vancomycin is not recommended for preoperative prophylaxis but may be considered as a component of an MRSA bundle to prevent surgical site infections.65

Our meta-analyses were the first to assess a bundle that included nasal decolonization and targeted glycopeptide prophylaxis for MRSA carriers. Other meta-analyses have assessed nasal decolonization or glycopeptide prophylaxis alone,66 67 68 and our results confirm the findings of the previous studies and extend these by including the results of recent studies. Future meta-analyses should assess other outcomes associated with these interventions. These outcomes could include duration of hospital stay since one group of researchers found that the mean duration of hospital stay was significantly shorter in those randomized to mupirocin and chorhexidine gluconate rather than to placebo.27 Future meta-analyses should also confirm our preliminary findings that these interventions do not open a niche for pathogens other than S aureusto fill, and should also analyze other patient populations such as those requiring trauma surgery to determine if these findings are generalizable to other surgical specialties.

Nasal decolonization protected against S aureus surgical site infections when all patients were decolonized and when only S aureus carriers were decolonized. Routine nasal decolonization of all surgical patients may be easier to implement and more cost effective than using cultures or polymerase chain reaction testing to screen patients preoperatively.69 None the less, it may be prudent to reserve mupirocin decolonization for patients who carry S aureus to prevent widespread mupirocin resistance.70Similarly, it may be prudent to do further research on targeted prophylaxis with vancomycin before including this bundle in clinical practice. Of note, the pooled relative risks assessing Gram positive surgical site infections were identical for both the decolonization studies and the bundle studies. Thus high quality studies such as cluster randomized trials are still needed to determine whether adding glycopeptide prophylaxis to nasal decolonization will further decrease the incidence of Gram positive surgical site infections.

In our sensitivity analyses we found that nasal decolonization was associated with a 1% risk difference and the bundle was associated with a 0.5% risk difference in Gram positive surgical site infections. Although these differences seem small, they are clinically significant considering that cardiac and orthopedic operations are common and surgical site infections are associated with considerable morbidity. Each year, approximately 300 000 cardiac operations and approximately 900 000 total joint arthroplasties are done in the United States alone.71 Thus these interventions could prevent 6000 to 12 000 surgical site infections per year in the United States and even more worldwide.

Limitations of this study

Our study has some limitations. Firstly, meta-analyses are only as valid as the studies that contribute to the pooled risk ratio. We included many studies that were simple before and after quasi-experimental studies. Additionally, none of the included studies adjusted statistically for potential confounders, thus confounding may be problem, especially among the observational studies. To mitigate this limitation, we performed subset analyses on the results of only randomized controlled trials. Secondly, we did not include studies that did not report or could not provide specific data on Gram positive infections, thus we may have excluded important decolonization and prophylaxis studies. However, nine of 15 contacted investigators submitted additional data for inclusion in the analyses. Thirdly, studies of the association between interventions and Gram positive surgical site infections were heterogeneous, and thus some of the meta-analysis results should be interpreted with caution. Once these studies were stratified by potential sources of heterogeneity, the stratified subsets were homogeneous. For example, nasal decolonization aims to decrease the incidence of endogenous S aureus surgical site infections. The association between nasal decolonization and Gram positive surgical site infections may have been different for studies in which S aureus caused most Gram positive surgical site infections compared with studies in which surgical site infections due to other Gram positive pathogens were common. Thus we limited heterogeneity by doing subset analyses that separated studies focusing on S aureus surgical site infections from those focusing on all Gram positive surgical site infections.

Conclusion

Surgical site infections caused by Gram positive bacteria may be prevented by decolonizing patients who carry S aureus in their nares and potentially by adding a glycopeptide to the usual prophylaxis using β lactam antibiotics for MRSA carriers. High quality randomized controlled trials or cluster randomized trials should be performed to further assess this bundle.

What is already known on this topic

  • Surgical site infections (SSIs) are potentially preventable adverse events of cardiac and orthopedic operations
  • SSIs significantly increase hospital length of stay, readmission rates, healthcare costs, and mortality rates
  • Clinicians and researchers have debated whether nasal decolonization or glycopeptide antibiotic prophylaxis reduce SSIs caused by Gram positive bacteria
  • Among patients undergoing cardiac or orthopedic surgery:
  • Nasal decolonization with mupirocin ointment was protective against Gram positive SSIs
  • Preoperative prophylaxis with anti-methicillin (meticillin) resistant Staphylococcus aureus (MRSA) antibiotics when given to all patients was not protective against Gram positive SSIs
  • A bundle that included nasal decolonization and anti-MRSA prophylaxis for MRSA carriers was significantly protective against Gram positive SSIs

What this study adds

 

  • Among patients undergoing cardiac or orthopedic surgery:
  • Nasal decolonization with mupirocin ointment was protective against Gram positive SSIs
  • Preoperative prophylaxis with anti-methicillin (meticillin) resistant Staphylococcus aureus (MRSA) antibiotics when given to all patients was not protective against Gram positive SSIs
  • A bundle that included nasal decolonization and anti-MRSA prophylaxis for MRSA carriers was significantly protective against Gram positive SSIs

Source: BMJ

 

 

Communication skills training for healthcare professionals working with people who have cancer. .


This is an updated version of a review that was originally published in the Cochrane Database of Systematic Reviews in 2004, Issue 2. People with cancer, their families and carers have a high prevalence of psychological stress which may be minimised by effective communication and support from their attending healthcare professionals (HCPs). Research suggests communication skills do not reliably improve with experience, therefore, considerable effort is dedicated to courses that may improve communication skills for HCPs involved in cancer care. A variety of communication skills training (CST) courses have been proposed and are in practice. We conducted this review to determine whether CST works and which types of CST, if any, are the most effective.

OBJECTIVES: To assess whether CST is effective in improving the communication skills of HCPs involved in cancer care, and in improving patient health status and satisfaction. SEARCH
METHODS: We searched the following electronic databases: Cochrane Central Register of Controlled Trials (CENTRAL) Issue 2, 2012, MEDLINE, EMBASE, PsycInfo and CINAHL to February 2012. The original search was conducted in November 2001. In addition, we handsearched the reference lists of relevant articles and relevant conference proceedings for additional studies.
SELECTION CRITERIA: The original review was a narrative review that included randomised controlled trials (RCTs) and controlled before-and-after studies. In this updated version, we limited our criteria to RCTs evaluating `CST` compared with `no CST` or other CST in HCPs working in cancer care. Primary outcomes were changes in HCP communication skills measured in interactions with real and/or simulated patients with cancer, using objective scales. We excluded studies whose focus was communication skills in encounters related to informed consent for research.
DATA COLLECTION AND ANALYSIS: Two review authors independently assessed trials and extracted data to a pre-designed data collection form. We pooled data using the random-effects model and, for continuous data, we used standardised mean differences (SMDs).
MAIN RESULTS: We included 15 RCTs (42 records), conducted mainly in outpatient settings. Eleven studies compared CST with no CST intervention, three studies compared the effect of a follow-up CST intervention after initial CST training, and one study compared two types of CST. The types of CST courses evaluated in these trials were diverse. Study participants included oncologists (six studies), residents (one study) other doctors (one study), nurses (six studies) and a mixed team of HCPs (one study). Overall, 1147 HCPs participated (536 doctors, 522 nurses and 80 mixed HCPs).Ten studies contributed data to the meta-analyses. HCPs in the CST group were statistically significantly more likely to use open questions in the post-intervention interviews than the control group (five studies, 679 participant interviews; P = 0.04, I(2) = 65%) and more likely to show empathy towards patients (six studies, 727 participant interviews; P = 0.004, I(2) = 0%); we considered this evidence to be of moderate and high quality, respectively. Doctors and nurses did not perform statistically significantly differently for any HCP outcomes.There were no statistically significant differences in the other HCP communication skills except for the subgroup of participant interviews with simulated patients, where the intervention group was significantly less likely to present `facts only` compared with the control group (four studies, 344 participant interviews; P = 0.01, I(2) = 70%).There were no significant differences between the groups with regard to outcomes assessing HCP `burnout`, patient satisfaction or patient perception of the HCPs communication skills. Patients in the control group experienced a greater reduction in mean anxiety scores in a meta-analyses of two studies (169 participant interviews; P = 0.02; I(2) = 8%); we considered this evidence to be of a very low quality.
AUTHORS’ CONCLUSIONS: Various CST courses appear to be effective in improving some types of HCP communication skills related to information gathering and supportive skills. We were unable to determine whether the effects of CST are sustained over time, whether consolidation sessions are necessary, and which types of CST programs are most likely to work. We found no evidence to support a beneficial effect of CST on HCP `burnout`, patients` mental or physical health, and patient satisfaction.

Source: Cochrane

Diagnostic accuracy of conventional or age adjusted D-dimer cut-off values in older patients with suspected venous thromboembolism: systematic review and meta-analysis.


Abstract

Objective To review the diagnostic accuracy of D-dimer testing in older patients (>50 years) with suspected venous thromboembolism, using conventional or age adjusted D-dimer cut-off values.

Design Systematic review and bivariate random effects meta-analysis.

Data sources We searched Medline and Embase for studies published before 21 June 2012 and we contacted the authors of primary studies.

Study selection Primary studies that enrolled older patients with suspected venous thromboembolism in whom D-dimer testing, using both conventional (500 µg/L) and age adjusted (age×10 µg/L) cut-off values, and reference testing were performed. For patients with a non-high clinical probability, 2×2 tables were reconstructed and stratified by age category and applied D-dimer cut-off level.

Results 13 cohorts including 12 497 patients with a non-high clinical probability were included in the meta-analysis. The specificity of the conventional cut-off value decreased with increasing age, from 57.6% (95% confidence interval 51.4% to 63.6%) in patients aged 51-60 years to 39.4% (33.5% to 45.6%) in those aged 61-70, 24.5% (20.0% to 29.7% in those aged 71-80, and 14.7% (11.3% to 18.6%) in those aged >80. Age adjusted cut-off values revealed higher specificities over all age categories: 62.3% (56.2% to 68.0%), 49.5% (43.2% to 55.8%), 44.2% (38.0% to 50.5%), and 35.2% (29.4% to 41.5%), respectively. Sensitivities of the age adjusted cut-off remained above 97% in all age categories.

Conclusions The application of age adjusted cut-off values for D-dimer tests substantially increases specificity without modifying sensitivity, thereby improving the clinical utility of D-dimer testing in patients aged 50 or more with a non-high clinical probability.

 

What is already known on this topic

  • A negative D-dimer test can rule out venous thromboembolism in patients with a non-high clinical probability
  • Since D-dimer levels increase with age, the proportion of false positive D-dimer test results for venous thromboembolism using conventional cut-off values (500 µg/L) increases in older patients and the specificity decreases
  • Age adjusted D-dimer cut-off values (age×10 µg/L) have therefore been introduced
  • This systematic review and meta-analysis established a poor specificity (around 15%) of D-dimer testing with the conventional cut-off value in the eldest patients (>80 years)
  • The application of the age adjusted cut-off value increased the specificity of the D-dimer test to 35% in the eldest patients, while hardly affecting the sensitivity
  • Use of age adjusted D-dimer cut-off values would result in imaging examinations being correctly avoided in 30-54% of older patients with a non-high clinical probability of venous thromboembolism.
  • Source: BMJ

What this study adds

Breast cancer detection and survival among women with cosmetic breast implants: systematic review and meta-analysis of observational studies.


Abstract

Objectives To evaluate whether the stage distribution among women diagnosed as having breast cancer differs between those who have received breast implants for cosmetic purposes and those with no implants and to evaluate whether cosmetic breast augmentation before the detection of breast cancer is a predictor of post-diagnosis survival.

Design Systematic review of observational studies with two meta-analyses.

Data sources Systematic search of the literature published before September 2012 conducted in Medline, Embase, Global health, CINAHL, IPAB, and PsycINFO.

Study selection Eligible publications were those that included women diagnosed as having breast cancer and who had had augmentation mammaplasty for cosmetic purposes.

Results The overall odds ratio of the first meta-analysis based on 12 studies was 1.26 (95% confidence interval 0.99 to 1.60; P=0.058; I2=35.6%) for a non-localized stage of breast cancer at diagnosis comparing women with implants who had breast cancer and women without implants who had breast cancer. The second meta-analysis, based on five studies, evaluated the relation between cosmetic breast implantation and survival. This meta-analysis showed reduced survival after breast cancer among women who had implants compared with those who did not (overall hazard ratio for breast cancer specific mortality 1.38, 95% confidence interval 1.08 to 1.75).

Conclusions The research published to date suggests that cosmetic breast augmentation adversely affects the survival of women who are subsequently diagnosed as having breast cancer. These findings should be interpreted with caution, as some studies included in the meta-analysis on survival did not adjust for potential confounders. Further investigations are warranted regarding diagnosis and prognosis of breast cancer among women with breast implants.

Discussion

This systematic review suggests that women with cosmetic breast implants have later stage tumors at diagnosis of breast cancer. In our second meta-analysis, the results show a higher risk of breast cancer specific mortality among women with breast cancer who have implants compared with women with breast cancer without implants. Nevertheless, the overall estimate should still be interpreted with caution because this meta-analysis included a relatively small number of studies. Of concern, three of five studies had unadjusted hazard ratios (not adjusted for age at diagnosis, or period of diagnosis) and all five studies were unadjusted for other potential confounding factors such as body mass index, which could translate into a biased estimate of the summary hazard ratio. A lack of adjustment for body mass index has previously been shown to lead to underestimation of the association between cosmetic breast implants and breast cancer mortality.18 Moreover, one study included in this meta-analysis assessed overall mortality rather than breast cancer specific mortality,39 which could have biased our summary estimate towards the null. The small number of studies and insufficient amount of follow-up time in these studies are suspected to limit statistical power to clearly evaluate survival rate patterns among augmented women. Given the limited evidence, no conclusion regarding breast cancer specific survival can be drawn and continued follow-up to further evaluate this question is particularly relevant.

Source: BMJ

Breast cancer detection and survival among women with cosmetic breast implants: systematic review and meta-analysis of observational studies


 

Objectives To evaluate whether the stage distribution among women diagnosed as having breast cancer differs between those who have received breast implants for cosmetic purposes and those with no implants and to evaluate whether cosmetic breast augmentation before the detection of breast cancer is a predictor of post-diagnosis survival.

Design Systematic review of observational studies with two meta-analyses.

Data sources Systematic search of the literature published before September 2012 conducted in Medline, Embase, Global health, CINAHL, IPAB, and PsycINFO.

Study selection Eligible publications were those that included women diagnosed as having breast cancer and who had had augmentation mammaplasty for cosmetic purposes.

Results The overall odds ratio of the first meta-analysis based on 12 studies was 1.26 (95% confidence interval 0.99 to 1.60; P=0.058; I2=35.6%) for a non-localized stage of breast cancer at diagnosis comparing women with implants who had breast cancer and women without implants who had breast cancer. The second meta-analysis, based on five studies, evaluated the relation between cosmetic breast implantation and survival. This meta-analysis showed reduced survival after breast cancer among women who had implants compared with those who did not (overall hazard ratio for breast cancer specific mortality 1.38, 95% confidence interval 1.08 to 1.75).

Conclusions The research published to date suggests that cosmetic breast augmentation adversely affects the survival of women who are subsequently diagnosed as having breast cancer. These findings should be interpreted with caution, as some studies included in the meta-analysis on survival did not adjust for potential confounders. Further investigations are warranted regarding diagnosis and prognosis of breast cancer among women with breast implants.

Discussion

This systematic review suggests that women with cosmetic breast implants have later stage tumors at diagnosis of breast cancer. In our second meta-analysis, the results show a higher risk of breast cancer specific mortality among women with breast cancer who have implants compared with women with breast cancer without implants. Nevertheless, the overall estimate should still be interpreted with caution because this meta-analysis included a relatively small number of studies. Of concern, three of five studies had unadjusted hazard ratios (not adjusted for age at diagnosis, or period of diagnosis) and all five studies were unadjusted for other potential confounding factors such as body mass index, which could translate into a biased estimate of the summary hazard ratio. A lack of adjustment for body mass index has previously been shown to lead to underestimation of the association between cosmetic breast implants and breast cancer mortality.18 Moreover, one study included in this meta-analysis assessed overall mortality rather than breast cancer specific mortality,39 which could have biased our summary estimate towards the null. The small number of studies and insufficient amount of follow-up time in these studies are suspected to limit statistical power to clearly evaluate survival rate patterns among augmented women. Given the limited evidence, no conclusion regarding breast cancer specific survival can be drawn and continued follow-up to further evaluate this question is particularly relevant.

Source: BMJ

Association between maternal serum 25-hydroxyvitamin D level and pregnancy and neonatal outcomes: systematic review and meta-analysis of observational studies.


Abstract

Objective To assess the effect of 25-hydroxyvitamin D (25-OHD) levels on pregnancy outcomes and birth variables.

Design Systematic review and meta-analysis.

Data sources Medline (1966 to August 2012), PubMed (2008 to August 2012), Embase (1980 to August 2012), CINAHL (1981 to August 2012), the Cochrane database of systematic reviews, and the Cochrane database of registered clinical trials.

Study selection Studies reporting on the association between serum 25-OHD levels during pregnancy and the outcomes of interest (pre-eclampsia, gestational diabetes, bacterial vaginosis, caesarean section, small for gestational age infants, birth weight, birth length, and head circumference).

Data extraction Two authors independently extracted data from original research articles, including key indicators of study quality. We pooled the most adjusted odds ratios and weighted mean differences. Associations were tested in subgroups representing different patient characteristics and study quality.

Results 3357 studies were identified and reviewed for eligibility. 31 eligible studies were included in the final analysis. Insufficient serum levels of 25-OHD were associated with gestational diabetes (pooled odds ratio 1.49, 95% confidence interval 1.18 to 1.89), pre-eclampsia (1.79, 1.25 to 2.58), and small for gestational age infants (1.85, 1.52 to 2.26). Pregnant women with low serum 25-OHD levels had an increased risk of bacterial vaginosis and low birthweight infants but not delivery by caesarean section.

Conclusion Vitamin D insufficiency is associated with an increased risk of gestational diabetes, pre-eclampsia, and small for gestational age infants. Pregnant women with low 25-OHD levels had an increased risk of bacterial vaginosis and lower birth weight infants, but not delivery by caesarean section.

 

Source: BMJ