On the properties of the hotelling��s T2 control chart with variable sampling intervals

When T ² control chart is used to monitor a process, it is usually assumed that the samples of size n ₀ is taken at constant intervals t ₀ . In this paper, we investigate the T ² control chart for monitoring the process mean vector when the sampling intervals are variable. Recent studies have shown that the variable sampling interval (VSI) scheme helps practitioners detect process shifts more quickly than the classical scheme Fixed Ratio Sampling (FRS). In this paper, it is assumed that the length of time the process remains in control is exponentially distributed.     

The cost-effectiveness of extended-release calcifediol versus paricalcitol for the treatment of secondary hyperparathyroidism in stage 3–4 CKD

Abstract

Aims: Patients with chronic kidney disease (CKD) not on dialysis frequently have vitamin D insufficiency (VDI) and secondary hyperparathyroidism (SHPT), which are associated with an increased risk of cardiovascular (CV) disease, fracture, CKD progression, and death. This study estimated the cost-effectiveness of extended-release calcifediol (ERC) vs paricalcitol for the treatment of patients with CKD stages 3–4 that have SHPT and VDI.

Materials and methods: An economic analysis of SHPT treatments among a hypothetical cohort of 1,000 patients with CKD Stage 3 and 4 with SHPT and VDI was developed to estimate differences in the rates and costs of CV events, fractures, CKD stage progression, and mortality in patients treated with ERC and paricalcitol. A Markov model was developed with 1-year cycles and a 5-year time horizon from a US Medicare payer perspective with costs valued in 2017?US dollars.

Results: The outcomes of the model were rates of clinical events, total costs, quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratio (ICER). Across a 1,000-person cohort, ERC was the dominant (less costly, more effective) treatment strategy when compared with paricalcitol. Treatment with ERC resulted in cost savings of $14.8?M (95% CI = –$10.0?M–$45.2?M) and an incremental gain of 340 QALYs (95% CI = 200–496) compared to treatment with paricalcitol.

Limitations: Bridging biochemical levels to clinical outcomes may not represent real-world risk of the clinical events modeled. Future real-world outcomes of patients treated with ERC and paricalcitol may be used to evaluate the model results.

Conclusions: This model demonstrated favorable short- and long-term clinical benefits associated with the use of ERC in patients with CKD Stage 3 and 4 with SHPT and VDI, suggesting ERC may be cost-effective from the Medicare perspective compared to paricalcitol.