scholarly journals Weighted Wilcoxon-Type Rank Test for Interval Censored Data

2013 ◽  
Vol 2013 ◽  
pp. 1-8
Author(s):  
Ching-fu Shen ◽  
Jin-long Huang ◽  
Chin-san Lee
Keyword(s):  
Failure Time ◽  
Sampling Technique ◽  
Rank Test ◽  
Test Statistics ◽  
Time Data ◽  
Interval Censored ◽  
Mean And Variance ◽  
The Mean ◽  
Better Than

Interval censored (IC) failure time data are often observed in medical follow-up studies and clinical trials where subjects can only be followed periodically, and the failure time can only be known to lie in an interval. In this paper, we propose a weighted Wilcoxon-type rank test for the problem of comparing two IC samples. Under a very general sampling technique developed by Fay (1999), the mean and variance of the test statistics under the null hypothesis can be derived. Through simulation studies, we find that the performance of the proposed test is better than that of the two existing Wilcoxon-type rank tests proposed by Mantel (1967) and R. Peto and J. Peto (1972). The proposed test is illustrated by means of an example involving patients in AIDS cohort studies.

A unified approach to variable selection for Cox’s proportional hazards model with interval-censored failure time data

2021 ◽  
pp. 096228022110092
Author(s):  
Mingyue Du ◽  
Hui Zhao ◽  
Jianguo Sun
Keyword(s):  
Variable Selection ◽  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Failure Time ◽  
Significant Feature ◽  
Failure Time Data ◽  
Time Data ◽  
Hazards Model ◽  
Interval Censored ◽  
Cox's Proportional Hazards Model

Cox’s proportional hazards model is the most commonly used model for regression analysis of failure time data and some methods have been developed for its variable selection under different situations. In this paper, we consider a general type of failure time data, case K interval-censored data, that include all of other types discussed as special cases, and propose a unified penalized variable selection procedure. In addition to its generality, another significant feature of the proposed approach is that unlike all of the existing variable selection methods for failure time data, the proposed approach allows dependent censoring, which can occur quite often and could lead to biased or misleading conclusions if not taken into account. For the implementation, a coordinate descent algorithm is developed and the oracle property of the proposed method is established. The numerical studies indicate that the proposed approach works well for practical situations and it is applied to a set of real data arising from Alzheimer’s Disease Neuroimaging Initiative study that motivated this study.

Abstract P606: Hemodynamic Predictors of Multiple Recurrent Strokes in the Patients With Prior Lacunar Stroke

Stroke ◽  
2021 ◽  
Vol 52 (Suppl_1) ◽  
Author(s):  
Adam H de Havenon ◽  
Alexandra Kvernland ◽  
Alen Delic ◽  
Ka-ho Wong ◽  
Nazanin Sheibani ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Logistic Regression ◽  
Failure Time ◽  
Recurrent Stroke ◽  
Cox Proportional Hazards Model ◽  
Lacunar Stroke ◽  
Blood Pressures ◽  
Recurrent Strokes ◽  
The Mean

Background: Recurrent stroke has higher morbidity and mortality than incident stroke. We evaluated hemodynamic risk factors for multiple recurrent strokes. Methods: We included patients in the SPS3 trial. The primary predictor was the top tertile, compared to the bottom tertile, of the mean systolic blood pressure (mSBP) and blood pressure variability represented as standard deviation (sdSBP) using blood pressures from day 30 of the trial to the end of follow-up. We excluded blood pressures from the first 30 days to reduce confounding from the trial’s intervention. We fit a logistic regression model to ≥2 recurrent strokes from day 30 to the end of follow-up and, to accurately analyze the multiple failure-time data, we ordered the multiple failure events to the Prentice, Williams and Peterson extension of the Cox proportional-hazards model. Results: We included 2,882 patients, of which 223 had a recurrent stroke and 41/223 had ≥2 recurrent strokes for a total of 272 strokes. The mean (SD) number of blood pressure readings was 78.0 (37.4). The etiology of the 272 strokes was 161 (59.2%) lacunar, 22 (8.1%) intracranial atherosclerosis, 10 (3.7%) extracranial atherosclerosis, 24 (8.8%) cardioembolic, and 55 (20.2%) cryptogenic or other. In both unadjusted and adjusted logistic regression models and PWP Cox models, the top tertile of sdSBP was consistently predictive of multiple recurrent strokes, while mSBP was not (Tables 1/2). Conclusions: We found that in patients with an index lacunar stroke, higher SBP variability, but not mean SBP, was predictive of multiple recurrent strokes of varying mechanisms.

Effects of Orthokeratology Lens On Axial Length Elongation in Myopia With Anisometropia Children

2021 ◽  
Author(s):  
Ziyang Chen ◽  
Kai-Ming Chen ◽  
Ying Shi ◽  
Zhao-Da Ye ◽  
Sheng Chen ◽  
...  
Keyword(s):  
Retrospective Study ◽  
Axial Length ◽  
Statistical Significance ◽  
Spherical Equivalent ◽  
Significant Difference ◽  
The Mean ◽  
The Difference ◽  
Better Than ◽  
Group 1

Abstract AimTo investigate the effect of orthokeratology (OK) lens on axial length (AL) elongation in myopia with anisometropia children.MethodsThirty-seven unilateral myopia (group 1) and fifty-nine bilateral myopia with anisometropia children were involved in this 1-year retrospective study. And bilateral myopia with anisometropia children were divided into group 2A (diopter of the lower SER eye under − 2.00D) and group 2B(diopter of the lower SER eye is equal or greater than − 2.00D). The change in AL were observed.The datas were analysed using SPSS 21.0.Results(1) In group 1, the mean baseline AL of the H eyes and L eye were 24.70 ± 0.89 mm and 23.55 ± 0.69 mm, respectively. In group 2A, the mean baseline AL of the H eyes and L eyes were 24.61 ± 0.84 mm and 24.00 ± 0.70 mm respectively. In group 2B, the mean baseline AL of the H eyes and L eyes were 25.28 ± 0.72 mm and 24.70 ± 0.74 mm. After 1 year, the change in AL of the L eyes was faster than the H eyes in group 1 and group 2A (all P<0.001).While the AL of the H eyes and L eyes had the same increased rate in group 2B. (2) The effect of controlling AL elongation of H eyes is consistent in three groups (P = 0.559).The effect of controlling AL elongation of L eyes in group 2B was better than that in group 1 and group 2A (P < 0.001). And the difference between group 1 and group 2A has no statistical significance. (3) The AL difference in H eyes and L eyes decreased from baseline 1.16 ± 0.55mm to 0.88 ± 0.68mm after 1 year in group 1.And in group 2A, the AL difference in H eyes and L eyes decreased from baseline 0.61 ± 0.34mm to 0.48 ± 0.28mm. There was statistically significant difference (all P<0.001). In group 2B, the baseline AL difference in H eyes and L eyes has no significant difference from that after 1 year (P = 0.069).ConclusionsMonocular OK lens is effective on suppression AL growth of the myopic eyes and reduce anisometropia value in unilateral myopic children. Binocular OK lenses only reduce anisometropia with the diopter of the low eye under − 2.00D. Binocular OK lenses cannot reduce anisometropia with the diopter of the low eye equal or greater than − 2.00D. Whether OK lens can reduce refractive anisometropia value is related to the spherical equivalent refractive of low refractive eye in bilateral myopia with anisometropia children after 1-year follow-up.

Primary Dermal Melanoma (PDM): Histological and Clinical Interdependence to Guide Therapy

2020 ◽  
pp. 120347542095763
Author(s):  
Hadas Zamir ◽  
Meora Feinmesser ◽  
Haim Gutman
Keyword(s):  
Mitotic Rate ◽  
Primary Treatment ◽  
Stage Iii ◽  
Sentinel Nodes ◽  
Time Period ◽  
Nodal Dissection ◽  
The Mean ◽  
Tight Correlation ◽  
Better Than

Background/purpose This study examined clinical and histological parameters of primary dermal melanoma (PDM) to aid in its distinction from dermal metastasis. Methods Retrospective analysis of a prospective cohort of PDM patients. Includes patients fulfilling the strict histologic criteria for PDM ( N = 9) and patients who did not, but clinically, unequivocally had an intradermal melanoma—clinical PDM (cPDM; N = 17). Histopathology slides were re-examined. Prognosticators and outcome measures were compared between groups. Sentinel nodes’ retrieval and wide local excision (WLE) were offered to all patients as primary treatment. Results 26 patients identified, 15 females with a median age of 69 years (range 3.5-85). Mean Breslow was 7.9 ± 5.7 mm (median 5.8, range 1.8-25.0), and the mean mitotic rate was 4.9 ± 3.8/mm2 (median 4.0, range 0-17). Initial treatment and follow-up were as for cutaneous melanoma. One patient in each group with a palpable stage III underwent primary radical dissection. Sentinel nodes were retrieved in all 20 lymphatic mappings performed and found to be metastatic in 5 (25%) patients. Treatment consisted of completion lymph-node dissection. At a median postoperative follow-up of 62 months (range 8-132), 20 patients were disease-free, including 6 of 7 patients with stage III disease at presentation. Six patients died all of cPDM; 5 of 6 patients had primary ulcerated or epidermal-abutting melanomas. Conclusions This is the first study to highlight cPDM. Diagnosis requires expert pathology review and a tight correlation to the clinical parameters. Patients seem to benefit from WLE with sentinel node retrieval and complete dissection when appropriate. However, clinical guidelines for dissection have changed since the time period of this retrospective review. Based on this series, complete nodal dissection in these melanomas is associated with better than expected outcome, for stage III disease.

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