Determinants of Orthostatic Hypotension in Type 2 Diabetes: Is Cardiac Autonomic Neuropathy the Main Factor?

OBJECTIVES: To evaluate the determinants of orthostatic hypotension (OH) in type 2 diabetes (T2D) and the usefulness of Δheart rate (HR)/Δsystolic blood pressure (SBP), index of cardiac baroreflex function, in identifying neurogenic OH. METHODS: In 208 participants with T2D, we diagnosed early cardiovascular autonomic neuropathy (CAN) and confirmed CAN according to 1 and 2 HR-based cardiovascular reflex tests (HR-CARTs). Through OH test we defined OH as SBP falls of ≥20 and ≥30 mm Hg with supine SBPs of <140 and ≥140 mm Hg, respectively. In participants with OH, we used the lying-to-standing and OH test and its diagnostic accuracy for neurogenic OH (as OH plus confirmed HR-CAN). RESULTS: OH was present in 25 participants and associated with lower HR-CART scores, higher glycosylated hemoglobin level, the presence of CAN, retinopathy, and peripheral vascular disease, the absence of hypertension, and physical activity (all, P < .05) but not with interfering drugs and ß-blockers. In a multiple logistic regression, HR-CAN was the main determinant of OH (odds ratio, 4.74) with physical activity and hypertension (odds ratios, 0.16 and 0.23; R2 = 0.22). ΔHR/ΔSBP had a good diagnostic accuracy for neurogenic OH (area under the receiver operating characteristic curve, 0.816 ± 0.087) and, at the cutoff of 0.5 bpm/mm Hg, a sensitivity of 100% and specificity of 63.2%. CONCLUSION: CAN remains the primary determinant of OH in T2D but does not explain all its variance. The index ΔHR/ΔSBP may represent a useful clinical tool to identify neurogenic OH.

Does the Relationship of the Autonomic Symptoms Questionnaire COMPASS 31 with Cardiovascular Autonomic Tests Differ between Type 1 and Type 2 Diabetes Mellitus?

Background: The aim was to investigate if autonomic symptoms questionnaire Composite Autonomic Symptom Score (COMPASS) 31 has different association with cardiovascular autonomic neuropathy (CAN) and diagnostic performance between type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM). Methods: Seventy-nine participants with T1DM and 140 with T2DM completed COMPASS 31 before cardiovascular reflex tests (CARTs) for CAN, and assessment of symptoms, signs, vibration, and thermal perception thresholds for diabetic polyneuropathy (DPN) diagnosis. Results: COMPASS 31 total weighted score (TWS) was similar in the two groups, but significantly associated with confirmed CAN only in T1DM (P=0.0056) and not T2DM group (P=0.1768) and correlated with CARTs score more strongly in T1DM (rho=0.356, P=0.0016) than in T2DM group (rho=0.084, P=0.3218) (P=0.016). Only in T1DM and not T2DM group, the area under the receiver operating characteristic curve (AUC) reached a fair diagnostic accuracy (>0.7) for confirmed CAN (0.73±0.07 vs. 0.61±0.08) and DPN (0.75±0.06 vs. 0.68±0.05), although without a significant difference. COMPASS 31 TWS (cut-off 16.44) reached acceptable diagnostic performance in T1DM, with sensitivity for confirmed CAN 81.2% and sensitivity and specificity for DPN 76.3% and 78%, compared to T2DM group (all <70%). AUC for DPN of orthostatic intolerance domain was higher in T1DM compared to T2DM group (0.73±0.05 vs. 0.58±0.04, P=0.027). Conclusion: COMPASS 31 is more weakly related to CAN in T2DM than in T1DM, with a fair diagnostic accuracy for confirmed CAN only in T1DM. This difference supports a multifactorial origin of symptoms and should be considered when using COMPASS 31.

Clinical scoring systems for the risk of cardiovascular autonomic neuropathy in type 1 and type 2 diabetes: A simple tool.

This study was aimed at developing a clinical risk score for cardiovascular autonomic neuropathy (CAN) for type 1 and type 2 diabetes. In a retrospective cross-sectional one-centre study in an unselected population, 115 participants with type 1 diabetes (age 41.1 ± 12.2 years) and 161 with type 2 diabetes (age 63.1 ± 8.9 years), well-characterized for clinical variables, underwent standard cardiovascular reflex tests (CARTs). Strength of associations of confirmed CAN (based on 2 abnormal CARTs) with clinical variables was used to build a CAN risk score. CAN risk score was based on resting heart rate, HbA1c, retinopathy, nephropathy, cardiovascular disease in both type 1 and type 2 diabetes, and on HDL cholesterol, systolic blood pressure, and smoking in type 1 diabetes or insulin treatment and physical activity in type 2 diabetes (range 0-10). In type 1 diabetes, CAN risk score showed an area under the ROC curve (AUC) of 0.890 ± 0.034, and at cut-off of 4 sensitivity of 88%, specificity of 74.4%, and negative predictive value (NPV) of 95.7% for confirmed CAN. In type 2 diabetes, CAN risk score showed an AUC of 0.830 ± 0.051 and at the cut-off of 4 sensitivity and specificity of 78.6% and 73.5%, respectively, and NPV of 97.3% for confirmed CAN. These newly developed CAN risk scores are accessible in clinical practice and, if confirmed in a validation study, they might identify asymptomatic individuals with diabetes at greater risk of CAN to be referred to CARTs, thus limiting the burden of a universal screening.

Expression study of candidate miRNAs and evaluation of their potential use as biomarkers of diabetic neuropathy.

Aim: To evaluate the expression of candidate miRNAs in relation to diabetic polyneuropathy (DPN) and cardiovascular autonomic neuropathy (CAN). Materials & methods: The expression of six candidate miRNAs has been evaluated in 49 Type 2 diabetes patients with neurological evaluation. Results: A higher expression of miR-128a was seen in patients with DPN compared with those without DPN (p = 0.015). miR-155 and miR-499a seemed to be down-expressed in patients with DPN (p = 0.04 and p = 0.05, respectively). A lower expression of miR-155 (p = 0.05) was observed even in patients with CAN with respect to CAN-negative. A higher expression of miR-155 was associated with the rs767649 polymorphism variant allele compared with the wild-type allele (p = 0.03). Conclusion: miR-128a, miR-155 and miR-499a might be involved in diabetic neuropathies development.

Mitochondrial DNA Copy Number in Peripheral Blood Is Reduced in Type 2 Diabetes Patients with Polyneuropathy and Associated with a MIR499A Gene Polymorphism.

Our aim was to evaluate in a cohort of 125 Italian patients with type 2 diabetes (T2D), who underwent neurological evaluation, the possible differences in the number of mitochondrial DNA copies (mtDNA) comparing positive and negative patients for cardiovascular autonomic neuropathy (CAN) or diabetic peripheral neuropathy (DPN) and comparing them with healthy controls. We also investigated a possible correlation of the number of mtDNA copies with the polymorphism rs3746444 of the MIR499A. T2D patients show a decrease in the number of mtDNA copies compared to healthy controls (p = 2 × 10-10). Dividing the T2D subjects by neurological evaluation, we found a significant mtDNA decrease in patients with DPN compared with those without (p = 0.02), while no differences were observed between subjects with and without CAN. Furthermore, the homozygous variant genotype for the polymorphism rs3746444 of MIR499A correlates with a decrease in the number of mtDNA copies, particularly in T2D patients (p = 0.009). Our data show a decrease in the number of mtDNA copies in subjects with T2D and suggest that this decrease is more evident in patients who develop DPN. Furthermore, the association of the variant allele of MIR499A with the number of mtDNA copies allows us to hypothesize a possible effect of this polymorphism in oxidative stress.

The diagnostic usefulness of the combined COMPASS 31 questionnaire and electrochemical skin conductance for diabetic cardiovascular autonomic neuropathy and diabetic polyneuropathy.

The study investigated the diagnostic performance for diabetic cardiovascular autonomic neuropathy (CAN) and diabetic polyneuropathy (DPN) of the combined use of composite autonomic symptom score (COMPASS) 31, validated questionnaire for autonomic symptoms of CAN, and electrochemical skin conductance (ESC), proposed for detecting DPN and CAN. One-hundred and two participants with diabetes (age 57 ± 14 years, duration 17 ± 13 years) completed the COMPASS 31 before assessing cardiovascular reflex tests (CARTs), neuropathic symptoms, signs, vibratory perception threshold (VPT), thermal thresholds (TT), and ESC using Sudoscan. Two patterns were evaluated: (a) the combined abnormalities in both tests (COMPASS 31+ESC), and (b) the abnormality in COMPASS 31 and/or ESC (COMPASS 31 and/or ESC). CAN (≥1 abnormal CART) and confirmed CAN (≥2 abnormal CARTs) were present in 28.1% and 12.5%, DPN (two abnormalities among symptoms, signs, VPT, and TT) in 52%, abnormal COMPASS 31 (total weighted score >16.44) in 48% and abnormal ESC (hands ESC <50 µS and/or feet ESC <70 µS) in 47.4%. Both the patterns-COMPASS 31+ESC and COMPASS 31 and/or ESC-were associated with CAN and DPN (P < .01). COMPASS 31 and ESC reached a sensitivity of 75% and 83% for confirmed CAN, and a specificity of 65% and 67% for DPN. When combining the tests, the sensitivity for CAN rose by up to 100% for CAN and the specificity up to 89% for DPN. The combination of the tests can allow a stepwise screening strategy for CAN, by suggesting CAN absence with combined normality, and prompting to CARTs with combined abnormality.

Morning blood pressure surge is associated with autonomic neuropathy and peripheral vascular disease in patients with diabetes.

Although vascular and autonomic nervous system have been involved in the regulation of morning surge in blood pressure (MBPS), data on clinical correlates of MBPS in diabetic population are scarce, in particular with regard to diabetic complications. This study was aimed at investigating predictors and correlates of MBPS in diabetes. In a cross-sectional study including 167 patients with diabetes (age 58.5 ± 11.1 years, duration 15.9 ± 12.1 years), clinical variables, diabetic and neuropathic complications, and MBPS (using 24-h ambulatory blood pressure monitoring) were measured. The upper quartile of MBPS (>30.5 mmHg) was associated with higher values of waist circumference (P = 0.027), triglycerides (P = 0.021), and Michigan Diabetic Neuropathy Score (P = 0.042), with lower HDL cholesterol (P = 0.030), and with the presence of cardiovascular autonomic neuropathy (CAN) (P = 0.016) and peripheral vascular disease (PVD) (P < 0.0001). In a logistic regression analysis, PVD (odds ratio: 10.2, P = 0.001), CAN (odds ratio: 6.09, P = 0.016), and diastolic blood pressure (BP) (odds ratio: 1.06, P = 0.022) predicted MBPS upper quartile (r2 = 0.20, P = 0.0005). In a multiple regression analysis, PVD (P = 0.002) and diastolic BP (P = 0.003) were the only determinants of MBPS (r2 = 0.20). MBPS upper quartile was associated with BP dipping (systolic BP day-night reduction > 10%) (P = 0.012), and MBPS was positively related to systolic (rho = 0.41, P < 0.0001) and diastolic BP day-night reduction. In conclusion, metabolic syndrome stigmata, diastolic BP, CAN and PVD are the main predictors of MBPS in the diabetic population. Excessive MBPS and nondipping are not concurrent 24-h BP alterations. Autonomic dysfunction might exert an exacerbating effect on MBPS phenomenon.

Association between a MIR499A polymorphism and diabetic neuropathy in type 2 diabetes.

AIMS: Diabetic polyneuropathy (DPN) and cardiovascular autonomic neuropathy (CAN) affect a large percentage of diabetic people and impact severely on quality of life. As it seems that miRNAs and their variations might play a role in these complications, we investigated whether the rs3746444 SNP in the MIR499A gene could be associated with susceptibility to DPN and/or CAN. METHODS: We analyzed 150 participants with type 2 diabetes. DNA was extracted from peripheral blood samples and genotyping was performed by TaqMan genotyping assay. Cardiovascular tests, MNSI-Q and MDNS for neuropathic symptoms and signs, VPT, and thermal thresholds were used for CAN and DPN assessment. We performed a genotype-phenotype correlation analysis. RESULTS: We observed that the GG genotype was associated with a higher risk of developing CAN (P=0.002 and OR=16.08, P=0.0005 and OR=35.02, for early and confirmed CAN, respectively) and DPN (P=0.037 and OR=6.56), after correction for BMI, sex, age, HbA1c and disease duration. Moreover, the GG genotype was associated with worse values of MDNS (P=0.017), VPT (P=0.01), thermal thresholds (P=0.01), and CAN score (P<0.001). A logistic multivariate analysis confirmed that MIR499A GG genotype, disease duration and HbA1c contributed to early CAN (R2=0.26), while the same variables and age contributed to DPN (R2=0.21). With a multiple linear regression, we observed that GG genotype (P=0.001) and disease duration (P=0.035) were the main variables contributing to the CAN score (R2=0.35). CONCLUSIONS: We described for the first time that the MIR499A genetic variation could be involved in diabetic neuropathies susceptibility. In particular, patients carrying the rs3746444 GG genotype had a higher risk of CAN development, together with a more severe form of CAN.

Recent advances in exploring the genetic susceptibility to diabetic neuropathy.

Diabetic polyneuropathy and cardiovascular autonomic neuropathy are common and disabling complications of diabetes. Although glycaemic control and cardiovascular risk factors are major contributory elements in its development, diabetic neuropathy recognizes a multifactorial influence and a multiplicity of pathogenetic mechanisms. Thus genetic and environmental factors may contribute to its susceptibility, each with a modest contribution, by targeting various metabolic and microvascular pathways whose alterations intervene in diabetic neuropathy pathogenesis. This review is aimed at describing major data from the available literature regarding genetic susceptibility to diabetic neuropathies. It provides an overview of the genes reported as associated with the development or progression of these complications, i.e. ACE, MTHFR, GST, GLO1, APOE, TCF7L2, VEGF, IL-4, GPX1, eNOS, ADRA2B, GFRA2, MIR146A, MIR128A. The identification of genetic susceptibility can help in both expanding the comprehension of the pathogenetic mechanisms of diabetic nerve damage and identifying biomarkers of risk prediction and response to therapeutic intervention.

Diabetic peripheral neuropathic pain is a stronger predictor of depression than other diabetic complications and comorbidities.

AIMS: To investigate the independent effect on depression of painless diabetic polyneuropathy, painful diabetic polyneuropathy, and general and diabetes-related comorbidities. METHODS: In 181 patients, the presence of painless diabetic polyneuropathy, painful diabetic polyneuropathy, comorbidities and depression was assessed using the Michigan Neuropathy Screening Instrument Questionnaire, the Michigan Diabetic Neuropathy Score, nerve conduction studies, the Douleur Neuropathique en 4 Questions, the Charlson Comorbidity Index and the Beck Depression Inventory-II. RESULTS: In all, 46 patients met the criteria of confirmed painless diabetic polyneuropathy and 25 of painful diabetic polyneuropathy. Beck Depression Inventory-II scores indicative of mild-moderate-severe depression were reached in 36 patients (19.7%). In a multiple logistic regression analysis (including age, sex, body mass index, being unemployed, duration, haemoglobin A1c, insulin treatment, systolic blood pressure, nephropathy, retinopathy, Charlson Comorbidity Index and painful diabetic polyneuropathy), female sex (odds ratio: 5.9, p = 0.005) and painful diabetic polyneuropathy (odds ratio: 4.6, p = 0.038) were the only independent predictors of depression. Multiple regression analysis, including Douleur Neuropathique en 4 Questions and Michigan Diabetic Neuropathy Score instead of painful diabetic polyneuropathy, showed that Douleur Neuropathique en 4 Questions, in addition to female sex, was a significant predictor of depressive symptoms severity (p =0.005). CONCLUSION: Painful diabetic polyneuropathy is a greater determinant of depression than other diabetes-related complications and comorbidities. Painful symptoms enhance depression severity more than objective insensitivity.

A novel association between nondipping and painful diabetic polyneuropathy.

OBJECTIVE: We hypothesized the meaningful coexistence of neuropathic pain and nondipping in painful diabetic polyneuropathy (PDPN). RESEARCH DESIGN AND METHODS: In 113 patients with PDPN, with painless diabetic polyneuropathy (DPN(+)) and without DPN (DPN(-)), neuropathic pain, sleep, risk for obstructive sleep apnea (OSA), autonomic function, and blood pressure (BP) circadian pattern were assessed using the Douleur Neuropathique en 4 Questions (DN4), the Medical Outcomes Study Sleep Scale, the Berlin Questionnaire, cardiovascular reflex tests, and ambulatory BP monitoring. RESULTS: Patients with PDPN showed higher nighttime systolic BP (130.4 ± 15.6 mmHg) than both DPN(-) (119.9 ± 10.6 mmHg; P < 0.0001) and DPN(+) patients (124.2 ± 12.3 mmHg; P < 0.05), and lower day-night difference (∆) in systolic BP (5.5 ± 6.5 vs. 8.6 ± 7.7%; P < 0.05) and diastolic BP than DPN(-) patients. In a stepwise regression analysis, orthostatic hypotension, high risk for OSA, and PDPN (DN4 interview) were independent determinants of ∆ in systolic BP (r = 0.46; P = 0.0001), ∆ in diastolic BP, and nighttime systolic BP. CONCLUSIONS: PDPN is associated with higher nocturnal systolic BP and impaired BP circadian pattern independent of pain-related comorbidities, suggesting a condition of high cardiovascular risk.

Common polymorphisms in MIR146a, MIR128a and MIR27a genes contribute to neuropathy susceptibility in type 2 diabetes.

Diabetic polyneuropathy (DPN) and cardiovascular autonomic neuropathy (CAN) are common type 2 diabetes complications with a large inter-individual variability in terms of clinical manifestations and severity. Our aim was to evaluate a possible involvement of genetic polymorphisms in miRNA regions in the susceptibility to DPN and CAN. Nine polymorphisms in miRNA genes were studied in a sample of 132 type 2 diabetes patients (T2D) analysed for DPN and 128 T2D patients analysed for CAN. A genotype-phenotype correlation analysis was performed. The T allele of rs11888095 single nucleotide polymorphism (SNP) in MIR128a was significantly associated with a higher risk (ORadj = 4.89, P adj = 0.02), whereas the C allele of rs2910164 SNP in MIR146a was associated with a lower risk to develop DPN (ORadj = 0.49, P adj = 0.09), respectively. A multivariate logistic regression analysis confirmed that both SNPs contribute to DPN (p < 0.001 and p = 0.01 for MIR128a and MIR146a, respectively). MIR128a SNP significantly contributed also to DPN score (p = 0.026). Rs895819 SNP in MIR27a was significantly associated with a higher risk to develop early CAN (P adj = 0.023 and ORadj = 3.43). The rs2910164 SNP in MIR146a showed a protective effect respect to early CAN (P adj = 0.052, ORadj = 0.32) and to confirmed CAN (P adj = 0.041, ORadj = 0.13). The same SNP resulted significantly associated with a lower CAN score and a higher E/I (p = 0.002 and p = 0.003, respectively). In conclusion, we described associations of MIR128a and MIR146a SNPs with DPN susceptibility and of MIR146a and MIR27a SNPs with CAN susceptibility. This is the first study showing that genetic variability in miRNA genes could be involved in diabetic neuropathies susceptibility.

MicroRNA genetic variations: association with type 2 diabetes.

MicroRNAs are small single-stranded molecules that have emerged as important genomic regulators in different pathways. Different studies have shown that they are implicated in the metabolism and glucose homeostasis, and therefore, they could also be involved in the pathogenesis of metabolic disorders such as type 2 diabetes (T2DM). The aim of this study was to verify whether genetic variations in candidate microRNA (miRNA or miR) genes could contribute to T2DM susceptibility. We have selected 13 miRNAs as candidate loci according to literature data and to a computational analysis. MicroRNA genes were analyzed by direct sequencing in a cohort of 163 Italian T2DM patients and 185 healthy controls. We identified 6 novel variants never described before and 9 SNPs already described in databases. Five newly identified variants were found only in the cases group. We performed a case/control association study to test the associations of particular alleles/genotypes of identified SNPs with the disease. Two polymorphisms were associated with T2DM susceptibility: in particular, the G allele of rs895819 in hsa-mir-27a has shown a significantly protective effect (OR = 0.58 and P = 0.008), while the G allele of rs531564 in hsa-mir-124a appears to be a risk allele (OR = 2.15, P = 0.008). This is the first report indicating that genetic polymorphisms in miRNA regions could contribute to T2DM susceptibility.

TCF7L2 gene polymorphisms and type 2 diabetes: association with diabetic retinopathy and cardiovascular autonomic neuropathy.

Type 2 diabetes (T2DM) is a complex disease resulting from the contribution of both environmental and genetic factors. Recently, the list of genes implicated in the susceptibility to T2DM has substantially grown, also as a consequence of the great development of the genome-wide association studies in the last decade. Common polymorphisms in TCF7L2 gene have shown to have a strong effect with respect to many other involved genes. The aims of our study were to confirm the role of TCF7L2 in the susceptibility to T2DM in the Italian population and to investigate whether TCF7L2 genotypes also contribute to the clinical phenotypes variability and to diabetic complications development. Three TCF7L2 polymorphisms (rs7903146, rs7901695 and rs12255372) have been analyzed by allelic discrimination assays in a cohort of 154 Italian patients with T2DM and 171 healthy controls. A case-control association study and a genotype-phenotype correlation study have been carried out. Consistent with previous studies, all three SNPs showed a strong association with susceptibility to T2DM, both at genotypic (P = 0.003, P = 0.004 and P = 0.012) and at allelic level (P = 0.0004, P = 0.0004 and P = 0.003). Moreover, we observed associations between TCF7L2 variants and the following diabetic complications: diabetic retinopathy, cardiovascular disease and coronary artery disease. We also found a strong correlation between the rs7903146 and the presence of cardiovascular autonomic neuropathy (P = 0.02 with a high OR = 8.28). In conclusion, our study, in addition to confirming the involvement of TCF7L2 gene in the T2DM susceptibility, has shown that TCF7L2 genetic variability also contributes to the development of diabetic complications such as retinopathy and cardiovascular autonomic neuropathy.

Clinical correlates of painful diabetic neuropathy and relationship of neuropathic pain with sensorimotor and autonomic nerve function.

BACKGROUND: This study investigated the clinical correlates of painful diabetic polyneuropathy (PDPN) and the relationship of neuropathic pain with sensorimotor and autonomic nerve function. METHODS: Seventy-eight diabetic patients with PDPN (PDPN(+)), 57 with non-painful diabetic polyneuropathy (DPN(+)), and 56 without diabetic polyneuropathy (DPN(-)) were prospectively studied. Autonomic neuropathy, neuropathic symptoms and signs, vibration perception threshold, and neuropathic pain were assessed using 4 cardiovascular tests, scoring systems for symptoms and signs (Michigan Diabetic Neuropathy Score, MDNS), Biothesiometer, and a numerical rating scale. RESULTS: Compared to DPN(+), PDPN(+) patients displayed higher BMI (P=0.0043), waist circumference (P=0.0057), neuropathy symptom score (P<0.0001), MDNS (P<0.0001), and lower Valsalva ratio (P=0.037). In a multiple logistic regression analysis including PDPN as the dependent variable and age, sex, body mass index (BMI), abdominal obesity, diabetes type, diabetes duration, HbA1c, blood pressure, triglycerides, smoking, peripheral arterial disease, Valsalva ratio and MDNS as the independent variables, BMI (OR 1.22, P=0.0012) and MDNS (OR 1.27, P=0.0005) were significantly and independently associated with PDPN. In a multivariate regression analysis including as independent variables also sex, age, diabetes type, diabetes duration and Valsalva ratio, 24-h pain score was significantly related to neuropathy symptom score (P=0.0011), MDNS (P=0.0158), and 10g monofilament (P=0.018). DISCUSSION: BMI and sensorimotor deficits were the main determinants of PDPN and, as a novel finding, neuropathic pain intensity was related to the degree of neuropathy deficits. Thus, some peculiarity exists in metabolic correlates of diabetic neuropathic pain compared to insensate neuropathy but painfulness can still coexist with insensitivity.

Reappraisal of the diagnostic role of orthostatic hypotension in diabetes.

OBJECTIVE: Given the controversial aspects of orthostatic hypotension (OH) testing in diabetes, we evaluated the diagnostic role for cardiac autonomic neuropathy (CAN) and for nondipping of OH, defined according to a fall in systolic blood pressure (BP) > or = 30 (30-OH) or > or = 20 mmHg (20-OH). METHODS: 164 diabetic patients underwent 24 hours BP monitoring, three heart rate cardiovascular tests, and OH test. RESULTS: Compared to 30 mmHg, the 20 mmHg criterion increased the frequency of OH from 11 to 19.5%. Both 30-OH and 20-OH were associated with CAN (chi (2) = 30.5, P < 0.0001, and chi (2) = 45.1, P < 0.0001, respectively) and nondipping (chi (2) = 31.7, P < 0.0001, and chi (2) = 17.2, P = 0.0001, respectively). ROC curve for orthostatic systolic BP fall provided an AUC of 0.79 +/- 0.04 (95% CI 0.70-0.86) for diagnosing CAN and of 0.77 +/- 0.05 (95% CI 0.66-0.86) for diagnosing nondipping. Both 30-OH and 20-OH showed a low sensitivity and high specificity for CAN [sensitivity 31%, specificity 98%, Likelihood Ratio for a positive result (LR(+)) 17.1; and sensitivity 50%, specificity 95%, LR(+) 9.3, respectively], and for nondipping (sensitivity 40%, specificity 96%, LR(+) 8.9, and sensitivity 47%, specificity 87%, LR(+) 3.5, respectively), having 30-OH a higher LR(+) in both cases. INTERPRETATION: OH had only moderate diagnostic accuracy, with high specificity and low sensitivity, for CAN, diagnosed on the basis of heart rate cardiovascular tests, and-as a novel finding-also for nondipping. A different definition of OH did not substantially affect its diagnostic characteristics, with just a slightly greater ability of the 30 mmHg criterion to estimate the probability of CAN and nondipping.