We have calculated the biological variation (BV) of different bone metabolism biomarkers on a large, well-described cohort of subjects. BV is important to calculate reference change value (or least significant change) which allows evaluating if the difference observed between two consecutive measurements in a patient is biologically significant or not.
BACKGROUND: Within-subject (CVI) and between-subject (CVG) biological variation (BV) estimates are essential in determining both analytical performance specifications (APS) and reference change values (RCV). Previously published estimates of BV for bone metabolism biomarkers are generally not compliant with the most up-to-date quality criteria for BV studies. We calculated the BV and RCV for different bone metabolism markers, namely β-isomerized C-terminal telopeptide of type I collagen (β-CTX), N-terminal propeptide of type I collagen (PINP), osteocalcin (OC), intact fibroblast growth factor 23 (iFGF-23), and uncarboxylated-unphosphorylated Matrix-Gla Protein (uCuP-MGP) using samples from the European Biological Variation Study (EuBIVAS).
METHODS: In the EuBIVAS, 91 subjects were recruited from six European laboratories. Fasting blood samples were obtained weekly for ten consecutive weeks. The samples were run in duplicate on IDS iSYS or DiaSorin Liaison instruments. The results were subjected to outlier and variance homogeneity analysis before CV-ANOVA was used to obtain the BV estimates.
RESULTS: We found no effect of gender upon the CVI estimates. The following CVI estimates with 95% confidence intervals (95% CI) were obtained: β-CTX 15.1% (14.4-16.0%), PINP 8.8% (8.4-9.3%), OC 8.9% (8.5-9.4%), iFGF23 13.9% (13.2-14.7%), and uCuP-MGP 6.9% (6.1-7.3%).
CONCLUSIONS: The EuBIVAS has provided updated BV estimates for bone markers, including iFGF23, which have not been previously published, facilitating the improved follow-up of patients being treated for metabolic bone disease.

BACKGROUND: Around-the-clock access to a known midwife is a distinct feature of Midwifery Group Practice (MGP) and caseload midwifery settings; although the literature suggests this aspect of working life may hinder recruitment and retention to this model of care. Mobile technologies, known as mHealth where they are used in health care, facilitate access and hence communication, however little is known about this area of midwifery practice.
OBJECTIVE: Which communication modalities are used, and most frequently, by MGP midwives and clients?
METHODS: A prospective, cross sectional design included a purposive sample of MGP midwives from an Australian tertiary maternity hospital. Data on modes of midwife-client contact were collected 24h/day, for two consecutive weeks, and included: visits, phone-calls, texts and emails. Demographic data were also collected.
RESULTS: Details about 1442 midwife-client contacts were obtained. The majority of contact was via text, between the hours of 07:00 and 14:59, with primiparous women, when the primary midwife was on-call. An average of 96 contacts per fortnight occurred.
CONCLUSIONS: The majority of contact was between the midwife and their primary clients, reiterating a key tenet of caseload models and confirming mobile technologies as a significant and evolving aspect of practice. The pattern of contact within social (or daytime) hours is reassuring for midwives considering caseload midwifery, who are concerned about the on-call burden. The use of text as the preferred communication modality raises issues regarding data security and retrieval, accountability, confidentiality and text management during off-duty periods. The development of Australian-wide guidelines to inform local policies and best practice is recommended.