The LEAP checklist for laboratory evaluation and analytical performance characteristics reporting of clinical measurement procedures.

Reporting a measurement procedure and its analytical performance following method evaluation in a peer-reviewed journal is an important means for clinical laboratory practitioners to share their findings. It also represents an important source of evidence base to help others make informed decisions about their practice. At present, there are significant variations in the information reported in laboratory medicine journal publications describing the analytical performance of measurement procedures. These variations also challenge authors, readers, reviewers, and editors in deciding the quality of a submitted manuscript. The International Federation of Clinical Chemistry and Laboratory Medicine Working Group on Method Evaluation Protocols (IFCC WG-MEP) developed a checklist and recommends its adoption to enable a consistent approach to reporting method evaluation and analytical performance characteristics of measurement procedures in laboratory medicine journals. It is envisioned that the LEAP checklist will improve the standardisation of journal publications describing method evaluation and analytical performance characteristics, improving the quality of the evidence base that is relied upon by practitioners.

Ensuring quality in 17OHP mass spectrometry measurement: an international study assessing isomeric steroid interference.

OBJECTIVES: Interference from isomeric steroids is a potential cause of disparity between mass spectrometry-based 17-hydroxyprogesterone (17OHP) results. We aimed to assess the proficiency of mass spectrometry laboratories to report 17OHP in the presence of known isomeric steroids. METHODS: A series of five samples were prepared using a previously demonstrated commutable approach. These samples included a control (spiked to 15.0 nmol/L 17OHP) and four challenge samples further enriched with equimolar concentrations of 17OHP isomers (11α-hydroxyprogesterone, 11ß-hydroxyprogesterone, 16α-hydroxyprogesterone or 21-hydroxyprogesterone). These samples were distributed to 38 participating laboratories that reported serum 17OHP results using mass spectrometry in two external quality assurance programs. The result for each challenge sample was compared to the control sample submitted by each participant. RESULTS: Twenty-six laboratories (68 % of distribution) across three continents returned results. Twenty-five laboratories used liquid chromatography-tandem mass spectrometry (LC-MS/MS), and one used gas chromatography-tandem mass spectrometry to measure 17OHP. The all-method median of the control sample was 14.3 nmol/L, ranging from 12.4 to 17.6 nmol/L. One laboratory had results that approached the lower limit of tolerance (minus 17.7 % of the control sample), suggesting the isomeric steroid caused an irregular result. CONCLUSIONS: Most participating laboratories demonstrated their ability to reliably measure 17OHP in the presence of the four clinically relevant isomeric steroids. The performance of the 12 (32 %) laboratories that did not engage in this activity remains unclear. We recommend that all laboratories offering LC-MS/MS analysis of 17OHP in serum, plasma, or dried bloodspots determine that the isomeric steroids are appropriately separated.

The LEAP checklist for laboratory evaluation and analytical performance characteristics reporting of clinical measurement procedures.

Reporting a measurement procedure and its analytical performance following method evaluation in a peer-reviewed journal is an important means for clinical laboratory practitioners to share their findings. It also represents an important source of evidence base to help others make informed decisions about their practice. At present, there are significant variations in the information reported in laboratory medicine journal publications describing the analytical performance of measurement procedures. These variations also challenge authors, readers, reviewers and editors in deciding the quality of a submitted manuscript. The International Federation of Clinical Chemistry and Laboratory Medicine Working Group on Method Evaluation Protocols (IFCC WG-MEP) developed a checklist and recommends its adoption to enable a consistent approach to reporting method evaluation and analytical performance characteristics of measurement procedures in laboratory medicine journals. It is envisioned that the LEAP checklist will improve the standardisation of journal publications describing method evaluation and analytical performance characteristics, improving the quality of the evidence base that is relied upon by practitioners.

The LEAP checklist for laboratory evaluation and analytical performance characteristics reporting of clinical measurement procedures.

Reporting a measurement procedure and its analytical performance following method evaluation in a peer-reviewed journal is an important means for clinical laboratory practitioners to share their findings. It also represents an important source of evidence base to help others make informed decisions about their practice. At present, there are significant variations in the information reported in laboratory medicine journal publications describing the analytical performance of measurement procedures. These variations also challenge authors, readers, reviewers, and editors in deciding the quality of a submitted manuscript. The International Federation of Clinical Chemistry and Laboratory Medicine Working Group on Method Evaluation Protocols (IFCC WG-MEP) developed a checklist and recommends its adoption to enable a consistent approach to reporting method evaluation and analytical performance characteristics of measurement procedures in laboratory medicine journals. It is envisioned that the LEAP checklist will improve the standardisation of journal publications describing method evaluation and analytical performance characteristics, improving the quality of the evidence base that is relied upon by practitioners.

The LEAP checklist for laboratory evaluation and analytical performance characteristics reporting of clinical measurement procedures.

Reporting a measurement procedure and its analytical performance following method evaluation in a peer-reviewed journal is an important means for clinical laboratory practitioners to share their findings. It also represents an important source of evidence base to help others make informed decisions about their practice. At present, there are significant variations in the information reported in laboratory medicine journal publications describing the analytical performance of measurement procedures. These variations also challenge authors, readers, reviewers, and editors in deciding the quality of a submitted manuscript. The International Federation of Clinical Chemistry and Laboratory Medicine Working Group on Method Evaluation Protocols (IFCC WG-MEP) developed a checklist and recommends its adoption to enable a consistent approach to reporting method evaluation and analytical performance characteristics of measurement procedures in laboratory medicine journals. It is envisioned that the Laboratory Evaluation and Analytical Performance Characteristics (LEAP) checklist will improve the standardisation of journal publications describing method evaluation and analytical performance characteristics, improving the quality of the evidence base that is relied upon by practitioners.

The LEAP checklist for Laboratory Evaluation and Analytical Performance characteristics reporting of clinical measurement procedures.

Reporting a measurement procedure and its analytical performance following method evaluation in a peer-reviewed journal is an important means for clinical laboratory practitioners to share their findings. It also represents an important source of evidence base to help others make informed decisions about their practice. At present, there are significant variations in the information reported in laboratory medicine journal publications describing the analytical performance of measurement procedures. These variations also challenge authors, readers, reviewers, and editors in deciding the quality of a submitted manuscript. The International Federation of Clinical Chemistry and Laboratory Medicine Working Group on Method Evaluation Protocols (IFCC WG-MEP) developed a checklist and recommends its adoption to enable a consistent approach to reporting method evaluation and analytical performance characteristics of measurement procedures in laboratory medicine journals. It is envisioned that the LEAP checklist will improve the standardisation of journal publications describing method evaluation and analytical performance characteristics, improving the quality of the evidence base that is relied upon by practitioners.

The LEAP checklist for Laboratory Evaluation and Analytical Performance Characteristics reporting of clinical measurement procedures.

Reporting a measurement procedure and its analytical performance following method evaluation in a peer-reviewed journal is an important means for clinical laboratory practitioners to share their findings. It also represents an important source of evidence base to help others make informed decisions about their practice. At present, there are significant variations in the information reported in laboratory medicine journal publications describing the analytical performance of measurement procedures. These variations also challenge authors, readers, reviewers, and editors in deciding the quality of a submitted manuscript.The International Federation of Clinical Chemistry and Laboratory Medicine Working Group on Method Evaluation Protocols (IFCC WG-MEP) developed a checklist and recommends its adoption to enable a consistent approach to reporting method evaluation and analytical performance characteristics of measurement procedures in laboratory medicine journals. It is envisioned that the LEAP checklist will improve the standardisation of journal publications describing method evaluation and analytical performance characteristics, improving the quality of the evidence base that is relied upon by practitioners.

Method evaluation in the clinical laboratory.

Method evaluation is one of the critical components of the quality system that ensures the ongoing quality of a clinical laboratory. As part of implementing new methods or reviewing best practices, the peer-reviewed published literature is often searched for guidance. From the outset, Clinical Chemistry and Laboratory Medicine (CCLM) has a rich history of publishing methods relevant to clinical laboratory medicine. An insight into submissions, from editors' and reviewers' experiences, shows that authors still struggle with method evaluation, particularly the appropriate requirements for validation in clinical laboratory medicine. Here, we consider through a series of discussion points an overview of the status, challenges, and needs of method evaluation from the perspective of clinical laboratory medicine. We identify six key high-level aspects of clinical laboratory method evaluation that potentially lead to inconsistency. 1. Standardisation of terminology, 2. Selection of analytical performance specifications, 3. Experimental design of method evaluation, 4. Sample requirements of method evaluation, 5. Statistical assessment and interpretation of method evaluation data, and 6. Reporting of method evaluation data. Each of these areas requires considerable work to harmonise the practice of method evaluation in laboratory medicine, including more empirical studies to be incorporated into guidance documents that are relevant to clinical laboratories and are freely and widely available. To further close the loop, educational activities and fostering professional collaborations are essential to promote and improve the practice of method evaluation procedures.

Longitudinal Stability of Vitamin D Status and Its Association With Bone Mineral Density in Middle-aged Australians.

Context: The skeletal effects of vitamin D remain controversial and it is uncertain whether variation in serum 25-hydroxyvitamin D (25OHD) levels over time influences bone mineral density (BMD). Objective: We evaluated longitudinal stability of serum 25OHD and associations with changes in BMD in participants aged 46-70 years at baseline. Methods: We studied 3698 Busselton Healthy Ageing Study participants (2040 female) with serum 25OHD and dual-energy x-ray absorptiometry (DXA) BMD assessments at baseline and at ∼6 years follow-up. Restricted cubic splines were used to evaluate associations between changes in 25OHD and BMD. Results: Mean season-corrected serum 25OHD was 81.3 ± 22.7 and 78.8 ± 23.1 nmol/L at baseline and 6 years, respectively, and showed moderate correlation (intraclass correlation coefficient: 0.724). Significant predictors of change in 25OHD concentration (Δ25OHD) included baseline 25OHD, change in body mass index and vitamin D supplementation at follow-up. Greater decline in serum 25OHD over time was associated with significantly greater reduction in BMD at total hip and femoral neck, but the magnitude of the differences was small (estimated differences 0.004 g/cm2 and 0.005-0.007 g/cm2, respectively, for lowest quartile of Δ25OHD compared with higher quartiles, adjusted for sex, baseline BMD, 25OHD, and demographics). No significant associations between Δ25OHD and lumbar spine BMD were observed. Increase in 25OHD levels was not associated with change in BMD. Conclusions: In this predominantly vitamin D-replete middle-aged cohort, serum 25OHD showed moderate longitudinal stability. Declining serum 25OHD over time was associated with greater reduction in BMD at the total hip and femoral neck.

Testosterone and exercise: effects on fitness, body composition, and strength in middle-to-older aged men with low-normal serum testosterone levels.

As men age, serum testosterone (T) concentrations decrease, as do fitness, strength, and lean mass. Whether testosterone treatment confers additive benefit to reverse these changes when combined with exercise training in middle-to-older aged men remains unclear. We assessed the effects of T treatment and exercise, alone and in combination, on aerobic capacity (V̇o2peak), body composition, and muscular strength in men 50-70 yr, waist circumference ≥95 cm and low-normal serum T (6-14 nmol·L-1). Participants (n = 80) were randomized to AndroForte5 (testosterone 5.0% wt/vol, 100 mg/2 mL) cream (T), or matching placebo (P), applied transdermally daily, and supervised center-based exercise (Ex) or no additional exercise (NEx), for 12-wk. Exercise increased V̇o2peak and strength versus nonexercise (V̇o2peak: T + Ex: +2.5 mL·kg-1·min-1, P + Ex: +3.2 mL·kg-1·min-1, P < 0.001; leg press: T + Ex: +31 kg, P + Ex: +24 kg, P = 0.006). T treatment did not affect V̇o2peak or strength. Exercise decreased total (T + Ex: -1.7, P + Ex: -2.3 kg, P < 0.001) and visceral fat (T + Ex: -0.1 kg, P + Ex: -0.3 kg, P = 0.003), and increased total (T + Ex: +1.4 kg, P + Ex: +0.7 kg, P = 0.008) and arm lean mass (T + Ex: +0.5 kg, P + Ex: +0.3 kg, P = 0.024). T treatment did not affect total or visceral fat, but increased total (T + Ex: +1.4 kg, T + NEx: +0.7 kg, P = 0.015), leg (T + Ex: +0.3 kg, T + NEx: +0.2 kg, P = 0.024), and arm lean mass (T + Ex: +0.5 kg, T + NEx: +0.2 kg, P = 0.046). T + Ex increased arm lean mass (T + Ex: +0.5 kg vs. P + NEx: -0.0 kg, P = 0.001) and leg strength (T + Ex: +31 kg vs. P + NEx: +12 kg, P = 0.032) compared with P + NEx, with no other additive effects. Exercise training was more effective than T treatment in increasing aerobic capacity and decreasing total and visceral fat mass. T treatment at therapeutic doses increased lean mass but conferred limited additional benefit when combined with exercise. Exercise should be evaluated as an antiaging intervention in preference to testosterone treatment in men.NEW & NOTEWORTHY We illustrate that exercise training generates superior outcomes to testosterone treatment for improving aerobic fitness, muscular strength, and total and visceral fat mass in men 50-70 yr with low-normal serum testosterone concentrations. Adding testosterone treatment to exercise did not provide any additive benefit for these variables. Testosterone treatment alone and exercise alone had similar impacts on lean mass. Therefore, men unable to exercise may obtain benefit from testosterone treatment alone to improve lean mass.

Effects of testosterone treatment, with and without exercise training, on ambulatory blood pressure in middle-aged and older men.

CONTEXT: With age, testosterone (T) and physical activity levels often decline in parallel. The effect of combining T treatment and exercise training on ambulatory blood pressure (ABP) is unclear. OBJECTIVE: To assess T and exercise effects, alone and in combination, on ABP in men aged 50-70 years, waist circumference ≥ 95 cm and low-normal serum T (6-14 nmol/L), without organic hypogonadism. DESIGN: A 2 × 2 factorial randomised, placebo-controlled study. INTERVENTION: Randomization to daily transdermal AndroForte5® (Testosterone 5.0%w/v, 100 mg in 2 ml) cream (T), or matching placebo (P) (double-blind), and to supervised exercise (Ex) or no additional exercise (NEx), for 12 weeks. RESULTS: Average 24-h systolic blood pressure (SBP) increased with T treatment (testosterone*time, p = .035). Average 24-h SBP increased in T+Ex (T+Ex:+3.0 vs. P+NEx: -3.0 mmHg, p = .026) driven by day-time changes (T+Ex:+3.5 vs. P+NEx: -3.0 mmHg, p = .026). There was an effect of T for 24-h average diastolic blood pressure (DBP, testosterone*time, p = .044) driven by the decrease in P+Ex (P+Ex: -3.9 vs. T+NEx: -0.5 mmHg, p = .015). Night-time DBP was lower with exercise (P+Ex: -4.0 vs. P+NEx: +0.7 mmHg, p = .032). The effect of exercise to lower night-time DBP was not apparent in the presence of T (T+Ex: -0.4 vs. P+NEx: +0.7 mmHg, p > .05). Ex increased average 24-h pulse pressure (PP, exercise*time, p = .022), largely during daytime hours (exercise*time, p = .013). CONCLUSIONS: There was a main effect of T to increase 24-h SBP, primarily seen when T was combined with Ex. Exercise alone decreased 24-h and night-time DBP; an effect attenuated by T. BP should be carefully assessed and monitored, when prescribing T treatment to middle-aged and older men, especially when combined with exercise training.

Investigating Potential Dose-Response Relationships between Vitamin D Status and Cognitive Performance: A Cross-Sectional Analysis in Middle- to Older-Aged Adults in the Busselton Healthy Ageing Study.

Low vitamin D status has been linked to adverse cognitive outcomes in older adults. However, relationships at higher levels remain uncertain. We aimed to clarify patterns of association between vitamin D status and cognitive performance, using flexible regression methods, in 4872 middle- to older-aged adults (2678 females) from the Busselton Healthy Ageing Study. Cross-sectional associations of serum levels of 25-hydroxyvitamin D (25OHD) and performance in cognitive domains were modelled using linear regression and restricted cubic splines, controlling for demographic, lifestyle, and health factors. Mean ± SD serum 25OHD levels were 78 ± 24 nM/L for women and 85 ± 25 nM/L for men. Increasing levels in women were associated with better global cognition (linear trend, p = 0.023) and attention accuracy (continuity of attention), with improvement in the latter plateauing around levels of 80 nM/L (nonlinear trend, p = 0.035). In men, increasing levels of serum 25OHD were associated with better attention accuracy (linear trend, p = 0.022), but poorer semantic verbal fluency (linear trend, p = 0.025) and global cognition (nonlinear trend, p = 0.015). We identified patterns of association between serum 25OHD levels and cognitive performance that may reflect early dose-response relationships, particularly in women. Longitudinal analyses extending through to older ages may help to clarify the nature, strength, and temporality of these relationships.

Influence of isotopically labeled internal standards on quantification of serum/plasma 17α-hydroxyprogesterone (17OHP) by liquid chromatography mass spectrometry.

Objectives Our recent survey of 44 mass spectrometry laboratories across 17 countries identified variation in internal standard (IS) choice for the measurement of serum/plasma 17α-hydroxyprogesterone (17OHP) by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The choice of IS may contribute to inter-method variations. This study evaluated the effect of two common isotopically labeled IS on the quantification of 17OHP by LC-MS/MS. Methods Three collaborating LC-MS/MS laboratories from Asia, Europe and Australia, who routinely measure serum 17OHP, compared two IS, (1) IsoSciences carbon-13 labeled 17OHP-[2,3,4-13C3], and (2) IsoSciences deuterated 17OHP-[2,2,4,6,6,21,21,21-2H]. This was performed as part of their routine patient runs using their respective laboratory standard operating procedure. Results The three laboratories measured 99, 89, 95 independent samples, respectively (up to 100 nmol/L) using the 13C- and 2H-labeled IS. The slopes of the Passing-Bablok regression ranged 0.98-1.00 (all 95% confidence interval [CI] estimates included the line of identity), and intercept of <0.1 nmol/L. Average percentage differences of -0.04% to -5.4% were observed between the two IS materials, which were less than the optimal bias specification of 7% determined by biological variation, indicating no clinically significant difference. The results of 12 Royal College of Pathologists of Australasia Quality Assurance Programs (RCPAQAP) proficiency samples (1-40 nmol/L) measured by the laboratories were all within the RCPAQAP analytical performance specifications for both IS. Conclusions Overall, the comparison between the results of 13C- and 2H-labeled IS for 17OHP showed good agreement, and show no clinically significant bias when incorporated into the LC-MS/MS methods employed in the collaborating laboratories.

U-shaped association of vigorous physical activity with risk of metabolic syndrome in men with low lean mass, and no interaction of physical activity and serum 25-hydroxyvitamin D with metabolic syndrome risk.

BACKGROUND: There is uncertainty over how lean mass, physical activity (PA) and 25-hydroxyvitamin D (25-OH-D) status interact on metabolic syndrome (MetS) risk in adults. AIMS: To test the hypothesis that these factors additively influence MetS risk. METHODS: Four thousand eight hundred and fifty-eight adults (54.6% female) mean ± SD age 58.0 ± 5.8 years, body mass index 28.1 ± 4.8 kg/m2 , resident in Busselton, Western Australia. PA assessed by questionnaire (all/total and vigorous), lean mass using dual energy X-ray absorptiometry (% total body mass), serum 25-OH-D via immunoassay, analysed using multivariable logistic regression. RESULTS: In men, lower total PA was associated with MetS (no vs >24 h/week odds ratio (OR) = 3.1; ≤8 vs >24 h/week OR = 1.8, both P < 0.001), as was lower lean mass (low vs high OR = 20.4; medium vs high OR = 7.4, both P < 0.001). Men with low lean mass exhibited a U-shaped relationship of vigorous PA with MetS risk (covariate-adjusted: 0 vs 4-8 h/week OR = 2.1, P = 0.037; >12 vs 4-8 h/week OR = 4.3, P = 0.002; interaction P = 0.039). In women, low PA (0 vs >24 h/week OR = 2.1, P = 0.003) and lean mass (low vs high OR = 13.1; medium vs high OR = 7.2, both P < 0.001) were associated with MetS risk. Low 25-OH-D status was associated with MetS in men (low vs high OR = 4.1; medium vs high OR = 2.3, both P < 0.001) and women (OR = 3.5 and 2.1 respectively, both P < 0.001) with no PA interaction. CONCLUSIONS: Men and women with high lean mass have low risk of MetS regardless of PA. Low lean mass identifies men who may benefit most from increasing PA, with an optimal level associated with lowest risk. 25-OH-D and PA do not interact on MetS risk.

Lower serum 25-hydroxyvitamin D is associated with colorectal and breast cancer, but not overall cancer risk: a 20-year cohort study.

Studies of the relationship between circulating 25-hydroxyvitamin D (25(OH)D) and cancer risk have been inconsistent. We hypothesized that serum 25(OH)D was associated with total non-skin cancer incidence and mortality, and/or specifically with colorectal, lung, breast or prostate cancer in an Australian cohort. Serum 25(OH)D was measured in 3818 participants (2166 females) in the 1994/1995 Busselton Health Survey aged 25 to 84 years at baseline. Cancer mortality and events over 20 years follow-up were determined by data linkage. The mean serum 25(OH)D concentration was 60.6 ±â€¯18.0 nmol/L, with 28%, 54% and 18% of participants in the lower (<50 nmol/L), middle (50-75 nmol/L) and higher (≥75 nmol/L) vitamin D status groups, respectively. During follow-up (excluding the first 2 years), 212 participants died from non-skin cancer and 634, 110 and 44 participants had non-skin, colorectal and lung cancer events, respectively; 113 women had breast cancer and 122 men had prostate cancer events. For colorectal cancer, lower circulating 25(OH)D was associated with significantly higher risk compared with the middle group (covariate-adjusted HR 1.62, 95% CI 1.04, 2.53). For breast cancer, women with a higher 25(OH)D level had lower risk than women in the middle group (HR 0.38, 95% CI 0.16, 0.89) and the lower group (HR 0.37, 95% CI 0.15, 0.89). Serum 25(OH)D was not associated with overall cancer death or event, or with lung or prostate cancer. In this community-based cohort, lower 25(OH)D levels were associated with increased risk of colorectal and breast cancer, but not overall cancer risk.

Low 25-Hydroxyvitamin D Concentration Is Not Associated With Refractive Error in Middle-Aged and Older Western Australian Adults.

PURPOSE: To investigate the association between serum 25-hydroxyvitamin D (25[OH]D) concentration and refractive error in a community-based cohort of adults aged 46 to 69 years. METHODS: Residents of the City of Busselton in Western Australia born between 1946 and 1964 were invited to participate. Participants underwent cycloplegic autorefraction and completed questionnaires on education, occupational sun exposure, and physical activity. Blood samples were collected and serum frozen at -80°C. Serum 25[OH]D concentration was measured by immunoassay. Data on 25[OH]D were deseasonalized and multivariate models built to analyze the association between 25[OH]D concentration and spherical equivalent and myopia, defined as spherical equivalent <-0.50 D. RESULTS: After exclusions, data were available for 4112 participants. Serum 25[OH]D concentration was not associated with spherical equivalent or myopia after adjustment for confounding factors (ß = -0.01, 95% confidence interval [CI]: -0.03 to -0.008, P = 0.25, and odds ratio = 1.02, 95% CI: 0.99 to 1.05, P = 0.12, respectively). When participants were classified into 25[OH]D groups of lower (<50 nmol/L), medium (≥50 to <75 nmol/L), and upper (≥75 nmol/L), the upper group had slightly greater myopic refractive error than the medium group (P = 0.02) but not the lower group, after adjustment for confounders. CONCLUSIONS: There was no substantial association between 25[OH]D levels and spherical equivalent or odds of myopia in this study. The association previously noted between low serum 25[OH]D level and myopia in younger Western Australians is not evident in later adulthood. TRANSLATIONAL RELEVANCE: This study provides further evidence suggesting that vitamin D levels are unrelated to myopia risk in adults and thus not a suitable target for myopia intervention.

Vitamin D and respiratory health in the Busselton Healthy Ageing Study.

BACKGROUND AND OBJECTIVE: The relationship between vitamin D and respiratory disease was examined by cross-sectional analysis of a large community-based sample. METHODS: Serum 25-hydroxyvitamin D (25OHD) and history of respiratory disease, symptoms (recorded by questionnaire) and spirometry were measured in 5011 adults aged 45-69 years. Adjustments were made for age, sex, season and smoking (Model A), plus body mass index (BMI) and physical activity level (Model B), plus history of chronic diseases (Model C). RESULTS: Mean (SD) age was 58 (SD 6) years with 45% males, 10% current smokers and 12% taking vitamin D supplements. The prevalence of 25OHD level <50 nmol/L was 8.0%. In all the three models, 25OHD <50 nmol/L was significantly associated with asthma (Model C: odds ratio (OR): 1.32; 95% CI: 1.00, 1.73), bronchitis (1.54; 1.17, 2.01), wheeze (1.37; 1.10, 1.71) and chest tightness (1.42; 1.10, 1.83). Participants with vitamin D level > 100 nmol/L had higher forced vital capacity (FVC) in all the three models (1.17% higher, compared with the 50-100 nmol/L group in Model C). CONCLUSION: Low levels of serum 25OHD were independently associated with asthma, bronchitis, wheeze and chest tightness after three levels of adjustment for potential confounders. Higher vitamin D levels were associated with higher levels of lung function.

Serum 25-hydroxyvitamin D as a predictor of mortality and cardiovascular events: A 20-year study of a community-based cohort.

OBJECTIVE: Prospective studies, mostly from Europe and North America, suggest that serum 25-hydroxyvitamin D (25(OH)D) is inversely associated with mortality and cardiovascular disease (CVD) risk. Data from other regions are limited, and threshold levels for adverse cardiovascular outcomes are uncertain. We examined serum 25(OH)D as a predictor of total mortality and cardiovascular outcomes in an Australian cohort. DESIGN: A 20-year, community-based cohort study. PATIENTS: Participants in the 1994/1995 Busselton Health Survey (n = 3946, baseline age 25-84 years). MEASUREMENTS: Baseline serum 25(OH)D and mortality and cardiovascular outcomes to 2014 obtained by record linkage. RESULTS: The mean serum 25(OH)D concentration was 60.6 ± 18.0 nmol/L. During 20-year follow-up (excluding the first 2 years), 889 participants died (including 363 from CVD) and 944 experienced a CVD event (including 242 with heart failure). In the full cohort, controlling for Framingham risk score variables, higher baseline 25(OH)D was associated with significantly reduced all-cause mortality (adjusted HR 0.83 per SD increment of 25(OH)D, 95% CI 0.77-0.90), CVD death (HR 0.85, 95% CI 0.74-0.96) and heart failure (HR 0.81, 95% CI 0.69-0.94), but not CVD events (HR 0.99, 0.92-1.07). In restricted cubic spline regression models, serum 25(OH)D below 65 and 55 nmol/L was associated with higher total mortality and higher CVD mortality/heart failure, respectively. In participants without CVD at baseline (n = 3220), results were similar, but hazard ratios were attenuated and associations with CVD mortality no longer significant. CONCLUSIONS: In an Australian community-based cohort, baseline vitamin D levels below 55-65 nmol/L are predictive of all-cause mortality, CVD death and heart failure.