***TASK***
the task is to simplify the input abstract of a biomedical literature

***INPUT***
the input is the abstract of a biomedical literature

***OUTPUT***
the output is the simplified abstract for the input abstract of a biomedical literature

***DOCUMENTATION***

***EXAMPLES***

Input: Sixteen studies (894 patients) were included. No formulation, route, or schedule of vitamin D compound was found to alter the mortality risk or need for dialysis. Vitamin D compounds significantly lowered serum PTH (4 studies, 153 patients: MD -49.34 pg/mL, 95% CI -85.70 to -12.97 (-5.6 pmol/L, 95% CI -9.77 to -1.48)) and were more likely to reduce serum PTH > 30% from baseline value (264 patients: RR 7.87, 95% CI 4.87 to 12.73). Vitamin D treatment was associated with increased end of treatment serum phosphorus (3 studies, 140 patients: MD 0.37 mg/dL, 95% CI 0.09, 0.66 (0.12 mmol/L, 95% CI 0.03, 0.21)) and serum calcium (5 studies, 184 patients: MD 0.20 mg/dL, 95% CI 0.17 to 0.23 (0.05 mmol/L, 95% CI 0.04 to 0.06)). Few data were available comparing intermittent with daily vitamin D administration, or other schedules of dosing. There are not sufficient data to determine the effect of vitamin D compounds on mortality and cardiovascular outcomes in people with CKD not requiring dialysis. While vitamin D compounds reduce serum PTH (49.3 pg/mL (5.6 pmol/L)) compared with placebo, the relative clinical benefits of PTH lowering versus treatment-related increases in serum phosphorus and calcium remain to be understood.
Output:

We identified 16 studies of vitamin D preparations in people with CKD and not requiring dialysis (less severe CKD) involving 894 people. No studies were designed to understand the effect of vitamin D therapy on risks of premature cardiovascular disease or mortality. Vitamin D agents lowered PTH significantly compared with no treatment, however also increased both calcium and phosphorus levels. Newer vitamin D therapies have not been compared with older vitamin compounds in CKD directly; whether they are associated with increased calcium and phosphorus is uncertain. In the future, new studies are required to assess outcomes important to patients, such as life expectancy and premature heart disease. It will also be important to know if vitamin D therapy should be used differently (differing target levels of PTH) in differing stages of CKD.