***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Vitamin D receptor activators ( VDRA ) may exert pleiotropic effects on cardiovascular disease , malignancy , and infections among dialysis patients , but recent studies have mainly focused on cardiovascular outcomes . Among 8,675 patients who started dialysis in 2007 and who survived until January 1 , 2010 , listed in the Renal Data Registry of the Japanese Society for Dialysis Therapy , 5,365 VDRA users were matched to 3,203 non-users based on clinical ly relevant variables at the end of 2009 using the coarsened exact matching procedure . Until December 31 , 2011 , a total of 1,128 deaths occurred , of which 468 ( 42 % ) were cardiovascular deaths , 229 ( 20 % ) were infection-related deaths , and 141 ( 12 % ) were malignancy-related deaths . Multivariable survival analyses accounting for intra-region correlation revealed that VDRA use was significantly associated with lower rates of infection- and malignancy-related deaths [ subhazard ratio 0.62 ( 95 % CI , 0.52–0.73 ) and 0.70 ( 95 % CI , 0.50–0.97 ) , respectively ] but not with cardiovascular death [ subhazard ratio 0.86 ( 95 % CI , 0.72–1.04 ) ] . Future r and omized clinical trials with a sufficient sample size and an adequate follow-up period are warranted to test the clinical effectiveness of  VDRA  on infection and malignancy , rather than cardiovascular disease , among dialysis patients Background Vitamin D has pleiotropic effects important for the proper functioning of multiple organ systems . We investigated whether serum 25-hydroxyvitamin D [ 25(OH)D ] levels influenced hospitalization-free survival in patients with chronic kidney disease ( CKD ) . Methods In this prospect i ve study , serum levels of 25(OH)D were measured in 210 patients with CKD in the winter of 2009 . Data regarding hospitalizations were collected over the subsequent 3 years . Results Vitamin D deficiency , as defined by a serum 25(OH)D level below 15 ng/mL , was observed in 76.7 % of the patients . The mean 25(OH)D serum level was 13.6 ± 7.8 ng/mL in predialysis patients ( n = 62 ) and 11.3 ± 6.7 ng/mL in dialysis patients ( n = 148 ) . During the follow-up , 107 patients ( 28 predialysis and 79 dialysis ) were hospitalized because of infectious ( 33.6 % ) or cardiovascular diseases ( 23.4 % ) .  Predialysis and  dialysis groups were divided into 2 subgroups based on the median 25(OH)D serum level . Kaplan – Meier analysis revealed that the risk of hospitalization was significantly lower in both predialysis and dialysis patients with above-median serum 25(OH)D levels ( log-rank test ; P = 0.043 and 0.002 , respectively ) . Multivariate Cox proportional hazards models also demonstrated that the risk of hospitalization was significantly lower for patients with higher serum 25(OH)D levels in both the predialysis ( hazard ratio , 0.963 ; 95 % confidence interval , 0.93–0.99 ) and dialysis groups ( hazard ratio , 0.955 ; 95 % confidence interval , 0.91–0.99 ) . Conclusion A lower serum 25(OH)D level predicted poorer hospitalization-free survival in both predialysis and dialysis CKD patients OBJECTIVE : Observational studies suggest that serum levels of 25-hydroxyvitamin D ( 25[OH]D ) are inversely associated with acute respiratory infections ( ARIs ) . We hypothesized that vitamin D supplementation of children with vitamin D deficiency would lower the risk of ARIs . METHODS : By using cluster r and omization , classrooms of 744 Mongolian schoolchildren were r and omly assigned to different treatments in winter ( January – March ) . This analysis focused on a subset of 247 children who were assigned to daily ingestion of unfortified regular milk ( control ; n = 104 ) or milk fortified with 300 IU of vitamin D3 ( n = 143 ) . This comparison was double-blinded . The primary outcome was the number of parent-reported ARIs over the past 3 months . RESULTS : At baseline , the median serum 25(OH)D level was 7 ng/mL ( interquartile range : 5–10 ng/mL ) . At the end of the trial , follow-up was 99 % ( n = 244 ) , and the median 25(OH)D levels of children in the control versus vitamin D groups was significantly different ( 7 vs 19 ng/mL ; P < .001 ) . Compared with controls , children receiving vitamin D reported significantly fewer ARIs during the study period ( mean : 0.80 vs 0.45 ; P = .047 ) , with a rate ratio of 0.52 ( 95 % confidence interval : 0.31–0.89 ) . Adjusting for age , gender , and history of wheezing , vitamin D continued to halve the risk of ARI ( rate ratio : 0.50 [ 95 % confidence interval : 0.28–0.88 ] ) . Similar results were found among children either below or above the median 25(OH)D level at baseline ( rate ratio : 0.41 vs 0.57 ; Pinteraction = .27 ) . CONCLUSIONS : Vitamin D supplementation significantly reduced the risk of ARIs in winter among Mongolian children with vitamin D deficiency Patients with ESRD commonly experience secondary hyperparathyroidism , a condition primarily managed with activated injectable vitamin D. The biologic effects of vitamin D , however , are widespread , and it is possible that activated injectable vitamin D alters survival in ESRD . This hypothesis was tested in a historical cohort study of incident hemodialysis patients who lived throughout the United States between January 1996 and December 1999 . The primary outcome was 2-yr survival among those who survived for at least 90 d after initiation of chronic hemodialysis . During this period , 51,037 chronic hemodialysis patients survived for at least 90 d from the initiation of hemodialysis  , and in the ensuing 2 yr , 37,173 received activated injectable vitamin D and 13,864  did not . At 2 yr , mortality rates were 13.8/100 person-years in the group that received injectable vitamin D compared with 28.6/100 person-years in the group that did not ( P < 0.001 ) . Cox proportional hazards analyses adjusting for several potential confounders and examining injectable vitamin D therapy as a time-dependent exposure suggested that compared with patients who did not receive injectable vitamin D , the 2-yr survival advantage associated with the group that did receive injectable vitamin D was 20 % ( hazard ratio , 0.80 ; 95 % confidence interval , 0.76 to 0.83 ) . The incidence of cardiovascular-related mortality was 7.6/100 person-years in the injectable vitamin D group , compared with 14.6/100 person-years in the non-vitamin D group ( P < 0.001 ) . The benefit of injectable vitamin D was evident in 48 of 49 strata examined , including those with low serum levels of intact parathyroid hormone and elevated levels of serum calcium and phosphorus , situations in which injectable vitamin D is often withheld . Repeating the entire analysis using marginal structural models to adjust for time-dependent confounding by indication yielded a survival advantage of 26 % ( hazard ratio , 0.74 ; 95 % confidence interval , 0.71 to 0.79 ) associated with the injectable vitamin D group . In this historical cohort study , chronic hemodialysis patients in the group that received injectable vitamin D had a significant survival advantage over patients who did not . R and omized clinical trials would permit definitive conclusions BACKGROUND Patients suffering from chronic kidney disease are at greater risk of developing infection than the normal population , and infections are the second cause of mortality after cardiovascular complications in this population . Some reports suggest that the intake of active vitamin D might be beneficial to prevent infections . Therefore , we aim ed to determine if the oral intake of vitamin D receptor activator ( VDRA ) is associated with a lower risk of infection-related hospitalization ( IRH ) among incident chronic hemodialysis patients . METHODS We conducted a nested case-control study in a cohort of 4933 patients initiating chronic hemodialysis between 1 January 2001 and 31 December 2007 in Quebec , Canada , using administrative data bases . We identified cases of hospital admission indicating an infection as main diagnosis on the hospital 's discharge sheet . Up to 10 controls were r and omly selected for each case . Association between oral VDRA use and risk of IRH was estimated using conditional logistic regression . RESULTS We identified 1136 cases of IRH and 10396 controls during the study period . The intake of VDRA was not associated with the risk of being hospitalized due to an infection ( odds ratio [ OR ] , 1.07 ; 95 % confidence interval [ CI ] , 0.95 - 1.20 ) . Using the prior 6-month cumulative dose of VDRA , we also found that a cumulative VDRA dose of less than 45 mcg ( OR , 1.05 ; 95%CI , 0.92 - 1.19 ) or greater than 45 mcg ( OR , 1.15 ; 95%CI , 0.96 - 1.36 ) was not associated with the IRH risk . CONCLUSIONS The oral intake of VDRA was not associated with the risk of IRH in incident hemodialysis patients BACKGROUND Hemodialysis patients who receive vitamin D receptor activator ( VDRA )  reportedly have better survival after infection than those who do not . However , the optimal route of its administration for minimizing death from infection remains unclear . METHODS This prospect i ve cohort study aim ed to compare the effectiveness of oral versus intravenous VDRA regarding infection-related mortality in 3372 hemodialysis patients . Eligible subjects were divided into the following three groups by route of administration of VDRA : oral ( n = 1868 ) , intravenous ( n = 492 ) and not administered ( n = 1012 ) . The effect of VDRA on infection-related mortality was examined using a Cox regression model with propensity score-based adjustments . RESULTS During follow-up ( median , 4.0 years ) , 118 study patients died of infection . There was a significantly lower incidence of death from infection in subjects who received intravenous VDRA  than in those who did not receive VDRA ; however , oral VDRA did not significantly reduce the risk of mortality from infection compared with those who did not receive VDRA [ hazard ratio ( HR ) for intravenous VDRA , 0.16 ; 95 % confidence interval ( CI ) , 0.10 - 0.25 , and HR for oral VDRA , 0.78 ; 95 % CI , 0.60 - 1.01 ] . Direct comparison between the oral and intravenous VDRA groups showed that the intravenous group had significantly better survival than the oral group ( HR , 0.39 ; 95 % CI , 0.27 - 0.62 ) . CONCLUSIONS Treatment with intravenous VDRA more effectively reduces the incidence of mortality from infection than oral VDRA in hemodialysis patients CONTEXT Observational studies have reported an inverse association between serum 25-hydroxyvitamin D ( 25-OHD ) levels and incidence of upper respiratory tract infections ( URTIs ) . However , results of clinical trials of vitamin D supplementation have been inconclusive . OBJECTIVE To determine the effect of vitamin D supplementation on incidence and severity of URTIs in healthy adults . DESIGN , SETTING , AND PARTICIPANTS R and omized , double-blind , placebo-controlled trial conducted among 322 healthy adults between February 2010 and November 2011 in Christchurch , New Zeal and . INTERVENTION Participants were r and omly assigned to receive an initial dose of 200,000 IU oral vitamin D3 , then 200,000 IU 1 month later , then 100,000 IU monthly ( n = 161 ) , or placebo administered in an identical dosing regimen ( n = 161 ) , for a total of 18 months . MAIN OUTCOME MEASURES The primary end point was number of URTI episodes . Secondary end points were duration of URTI episodes , severity of URTI episodes , and number of days of missed work due to URTI episodes . RESULTS The mean baseline 25-OHD level of participants was 29 ( SD , 9 ) ng/mL. Vitamin D supplementation result ed in an increase in serum 25-OHD levels that was maintained at greater than 48 ng/mL throughout 
    Output:
    
Conclusions High or normal serum levels of 25(OH)D and the use of vitamin D , particularly VDRA , were each associated with a lower risk of composite infection in long-term dialysis patients