A Breast Cancer Polygenic Risk Score Is Feasible for Risk Stratification in the Norwegian Population

BACKGROUND

Statistical associations of numerous single nucleotide polymorphisms with breast cancer (BC) have been identified in genome-wide association studies (GWAS). Recent evidence suggests that a Polygenic Risk Score (PRS) can be a useful risk stratification instrument for a BC screening strategy, and a PRS test has been developed for clinical use. The performance of the PRS is yet unknown in the Norwegian population.

AIM

To evaluate the performance of PRS models for BC in a Norwegian dataset.

METHODS

We investigated a sample of 1053 BC cases and 7094 controls from different regions of Norway. PRS values were calculated using four PRS models, and their performance was evaluated by the area under the curve (AUC) and the odds ratio (OR). The effect of the PRS on the age of onset of BC was determined by a Cox regression model, and the lifetime absolute risk of developing BC was calculated using the iCare tool.

RESULTS

The best performing PRS model included 3820 SNPs, which yielded an AUC = 0.625 and an OR = 1.567 per one standard deviation increase. The PRS values of the samples correlate with an increased risk of BC, with a hazard ratio of 1.494 per one standard deviation increase (95% confidence interval of 1.406-1.588). The individuals in the highest decile of the PRS have at least twice the risk of developing BC compared to the individuals with a median PRS. The results in this study with Norwegian samples are coherent with the findings in the study conducted using Estonian and UK Biobank samples.

CONCLUSION

The previously validated PRS models have a similar observed accuracy in the Norwegian data as in the UK and Estonian populations. A PRS provides a meaningful association with the age of onset of BC and lifetime risk. Therefore, as suggested in Estonia, a PRS may also be integrated into the screening strategy for BC in Norway.

Different Effects of Aging on Intraocular Pressures Measured by Three Different Tonometers

This study aimed to compare intraocular pressures (IOP) using different tonometers, Goldmann applanation (IOP_GAT), non-contact (IOP_NCT), and rebound (IOP_RBT), and to assess the effects of aging and central corneal thickness (CCT) on the measurements. The IOP_GAT, IOP_NCT, IOP_RBT, mean patient age (65.1 ± 16.2 years), and CCT (521.7 ± 39.2 µm) were collected retrospectively from 1054 eyes. The differences among IOPs were compared by the paired t-test. Possible correlations between devices, age, and CCT were assessed by linear regression analyses. The effects of age and CCT on the IOP reading were assessed by mixed-effects regression models. The IOP_GAT values were 2.4 and 1.4 mmHg higher than IOP_NCT and IOP_RBT, respectively; the IOP_NCT was 1.0 mmHg lower than IOP_RBT (p < 0.0001 for all comparisons). The IOPs measured by each tonometer were highly correlated with each other (r = 0.81–0.90, t = 45.2–65.5). The linear regression analyses showed that age was negatively correlated with IOP_NCT (r = −0.12, t = −4.0) and IOP_RBT (r = −0.14, t = −4.5) but not IOP_GAT (r = 0.00, t = −0.2); the CCT was positively correlated with IOP_GAT (r = 0.13, t = 4.3), IOP_NCT (r = 0.29, t = 9.8), and IOP_RBT (r = 0.22, t = 7.2). The mixed-effect regression models showed significant negative correlations between age and IOP_NCT (t = −2.6) and IOP_RBT (t = −3.4), no correlation between age and IOP_GAT (t = 0.2), and a significant positive correlation between CCT and the tonometers (t = 3.4–7.3). No differences between IOP_GAT and IOP_RBT were seen at the age of 38.8 years. CCT affects IOPs from all tonometers; age affects IOP_NCT and IOP_RBT in different degrees. IOP_RBT tended to be higher than IOP_GAT in young subjects, but this stabilized in middle age and became higher in older subjects.

Limbal rebound tonometry: clinical comparisons and applications

PURPOSE

The accuracy of contact tonometry may be compromised in cases with disorders affecting central corneal bio-mechanical properties. This study examined the reliability of rebound tonometry (RT) on the area of corneo-scleral limbus, instead of the conventional central corneal area, and the correlation of findings with ocular biometric parameters.

METHODS

This is a prospective cross-sectional study performed at the Department of Ophthalmology of the University Hospital of Heraklion, in Crete, Greece. Consecutive cataract surgery candidates without concomitant ocular pathology, apart from cataract, were included. RT was performed on the central cornea (central RT, CRT) as well as on the limbus and scleral spur area (limbal RT, LRT). Findings were correlated with Goldmann applanation tonometry (GAT) as well as axial length (AL), central corneal thickness (CCT), and corneal curvature (CC) measurements.

RESULTS

LRT readings were significantly correlated with central CRT as well as with GAT readings, whereas respective correlations with other parameters examined were not statistically significant.

CONCLUSIONS

LRT may be used as an alternative tool in clinical practice to determine intraocular pressure when conventional devices and techniques might be inadequate or unreliable.

Agreement among Goldmann applanation tonometer, iCare, and Icare PRO rebound tonometers; non-contact tonometer; and Tonopen XL in healthy elderly subjects

PURPOSE

To evaluate the inter-device agreement among the Goldmann applanation tonometer (GAT), iCare and Icare PRO rebound tonometers, non-contact tonometer (NCT), and Tonopen XL tonometer.

METHODS

Sixty healthy elderly subjects were enrolled. The intraocular pressure (IOP) in each subject's right eye was measured thrice using each of the five tonometers. Intra-device agreement was evaluated by calculating intraclass correlation coefficients (ICCs). Inter-device agreement was evaluated by ICC and Bland-Altman analyses.

RESULTS

ICCs for intra-device agreement for each tonometer were >0.8. IOP as measured by iCare (mean ± SD, 11.6 ± 2.5 mmHg) was significantly lower (p < 0.05) than that measured by GAT (14.0 ± 2.8 mmHg), NCT (13.6 ± 2.5 mmHg), Tonopen XL (13.7 ± 4.1 mmHg), and Icare PRO (12.6 ± 2.2 mmHg; Bonferroni test). There was no significant difference in mean IOP among GAT, NCT, and Tonopen XL. Regarding inter-device agreement, ICC was lower between Tonopen XL and other tonometers (all ICCs < 0.4). However, ICCs of GAT, iCare, Icare PRO, and NCT showed good agreement (0.576-0.700). The Bland-Altman analysis revealed that the width of the 95% limits of agreement was larger between the Tonopen XL and the other tonometers ranged from 14.94 to 16.47 mmHg. Among the other tonometers, however, the widths of 95% limits of agreement ranged from 7.91 to 9.24 mmHg.

CONCLUSION

There was good inter-device agreement among GAT, rebound tonometers, and NCT. Tonopen XL shows the worst agreement with the other tonometers; therefore, we should pay attention to its' respective IOP.

CLINICAL TRIAL REGISTRATION

Japan Clinical Trials Register; number: UMIN000011544.

Intraocular pressure measurement after DSAEK by iCare, Goldmann applanation and dynamic contour tonometry: A comparative study

PURPOSE

Corneal thickness inevitably increases following Descemet's stripping automated endothelial keratoplasty (DSAEK), owing to the addition of a donor graft. The current study compares different devices in assessing post-DSAEK intraocular pressure (IOP).

METHODS

We compared IOP values measured by the Goldmann tonometry (GAT), iCare rebound tonometry (iCare) and Pascal dynamic contour tonometry (PDCT) in eyes following DSAEK. Agreement between measurements was calculated with correlation analysis and Bland-Altman plots. Effects of keratometry, central, thickness (CCT), endothelial cell density (ECD) and axial length on IOP measurements were assessed with Pearson's correlation.

RESULTS

Twenty eyes of 20 patients (mean age 74.3±14.4, 14 females) post-DSAEK were included in this study. There was a high concordance between the IOP readings obtained by the three devices: a strong and significant correlation was found between GAT and PDCT (r=0.94, P<0.001) GAT and iCare (r=0.86, P<0.001) and iCare with PDCT (r=0.81, P<0.001). However, the iCare measurements were significantly and consistently lower than that obtained with GAT (ΔIOP=1.68±2.0, P=0.002, 95% CI: 0.7-2.6) and with PDCT (ΔIOP=1.61±2.5, P=0.01, 95% CI: 0.4-2.8). CCT, ECD, CCT, AXL, corneal curvature or astigmatism did not influence IOP measurement by any instrument.

CONCLUSIONS

IOP measurement with three different techniques (applanation, rebound and dynamic contour) showed good correlations, despite an increased corneal thickness following DSAEK. However, the iCare, which is based on a rebound tonometry showed significant lower IOP then the two other methods. This should be taken into account when evaluating patients post DSAEK.