Interval estimation for operating characteristic of continuous biomarkers with controlled sensitivity or specificity.

The receiver operating characteristic (ROC) curve provides a comprehensive performance assessment of a continuous biomarker over the full threshold spectrum. Nevertheless, a medical test often dictates to operate at a certain high level of sensitivity or specificity. A diagnostic accuracy metric directly targeting the clinical utility is specificity at the controlled sensitivity level, or vice versa. While the empirical point estimation is readily adopted in practice, the nonparametric interval estimation is challenged by the fact that the variance involves density functions due to estimated threshold. In addition, even with a fixed threshold, many standard confidence intervals including the Wald interval for binomial proportion could have erratic behaviors. In this article, we are motivated by the superior performance of the score interval for binomial proportion and propose a novel extension for the biomarker problem. Meanwhile, we develop exact bootstrap and establish consistency of the bootstrap variance estimator. Both single-biomarker evaluation and two-biomarker comparison are investigated. Extensive simulation studies were conducted, demonstrating competitive performance of our proposals. An illustration with aggressive prostate cancer diagnosis is provided.

Challenge of balancing duration of stay and readmissions in children's operation.

BACKGROUND: Surgeons balance competing interests of minimizing duration of stay with readmissions. Complications that occur early after discharge often result in readmissions. This study examines the relationship between duration of stay, timing of complications, and readmission risk. METHODS: Cases from the 2012-2014 National Surgical Quality Improvement Project-Pediatric were organized into 30 procedural groups. Procedures where duration of stay approximated the median day of complication were identified. A theoretical model was applied to minimize readmissions by extending duration of stay. RESULTS: From 30 procedure groups, 3 were identified where duration of stay approximated median day of compilations: complicated appendectomy, antireflux operation, and abdominal operation without bowel resection. The complicated appendectomy readmission rate drops from 12.2% to 8.2%, increasing duration of stay from 3 to 8 days at the cost of 16,428 additional hospital days among 4,740 patients (3.5 days/patient). Readmission optimization tapers after duration of stay of 8 days. Similar findings were observed for antireflux operation and abdominal operation without bowel resection with readmission optimization at duration of stay of 5 days (2.6 days/patient) and 7 days (5.3 days/patient), respectively. CONCLUSION: Our theoretical model aimed at balancing readmissions by extending duration of stay to capture early complications results in a substantial increase in hospital days illustrating the conflict between competing quality metrics and limited resources.

Perioperative Visual Loss in Spine Fusion Surgery: Ischemic Optic Neuropathy in the United States from 1998 to 2012 in the Nationwide Inpatient Sample.

BACKGROUND: Perioperative ischemic optic neuropathy (ION) causes visual loss in spinal fusion. Previous case-control studies are limited by study size and lack of a random sample. The purpose of this study was to study trends in ION incidence in spinal fusion and risk factors in a large nationwide administrative hospital database. METHODS: In the Nationwide Inpatient Sample for 1998 to 2012, procedure codes for posterior thoracic, lumbar, or sacral spine fusion and diagnostic codes for ION were identified. ION was studied over five 3-yr periods (1998 to 2000, 2001 to 2003, 2004 to 2006, 2007 to 2009, and 2010 to 2012). National estimates were obtained using trend weights in a statistical survey procedure. Univariate and Poisson logistic regression assessed trends and risk factors. RESULTS: The nationally estimated volume of thoracic, lumbar, and sacral spinal fusion from 1998 to 2012 was 2,511,073. ION was estimated to develop in 257 patients (1.02/10,000). The incidence rate ratio (IRR) for ION significantly decreased between 1998 and 2012 (IRR, 0.72 per 3 yr; 95% CI, 0.58 to 0.88; P = 0.002). There was no significant change in the incidence of retinal artery occlusion. Factors significantly associated with ION were age (IRR, 1.24 per 10 yr of age; 95% CI, 1.05 to 1.45; P = 0.009), transfusion (IRR, 2.72; 95% CI, 1.38 to 5.37; P = 0.004), and obesity (IRR, 2.49; 95% CI, 1.09 to 5.66; P = 0.030). Female sex was protective (IRR, 0.30; 95% CI, 0.16 to 0.56; P = 0.0002). CONCLUSIONS: Perioperative ION in spinal fusion significantly decreased from 1998 to 2012 by about 2.7-fold. Aging, male sex, transfusion, and obesity significantly increased the risk.

Corneal abrasion in hysterectomy and prostatectomy: role of laparoscopic and robotic assistance.

BACKGROUND: Radical prostatectomy (RP) is most commonly performed laparoscopically with a robot (robotic-assisted laparoscopic radical prostatectomy, R/PROST). Hysterectomy, which may be open hysterectomy (O/HYST) or laparoscopic hysterectomy (L/HYST), has been increasingly frequently done via robot (R/HYST). Small case series suggest increased corneal abrasions (CAs) with less invasive techniques. METHODS: The authors identified RP (166,942), O/HYST (583,298), or L/HYST (216,890) discharges with CA in the Nationwide Inpatient Sample (2000-2011). For 2009-2011, they determined odds ratios (ORs) and 95% confidence intervals (CIs) for CA, in R/PROST, non-R/PROST, L/HYST, O/HYST, and R/HYST. Uni- and multivariate models studied CA risk depending on surgical procedure, age, race, year, chronic illness, and malignancy. RESULTS: In 2000-2011, 0.18% RP, 0.13% L/HYST, and 0.03% O/HYST sustained CA. Compared with 17,554 non-R/PROSTs (34 abrasions, 0.19%) in 2009-2011, OR was not significantly higher in 28,521 R/PROSTs (99, 0.35%; OR 1.508; CI 0.987 to 2.302; P < 0.057). CA significantly increased in L/HYST (70/51,323; 0.136%) versus O/HYST (70/191,199; 0.037%; OR 3.821; CI 2.594 to 5.630; P < 0.0001), further increasing in R/HYST (63/21, 213; 0.297%; OR 6.505; CI 4.323 to 9.788; P < 0.0001). For hysterectomy, risk of CA increased with age (OR 1.020; CI 1.007 to 1.034; P < 0.003) and number of chronic conditions (OR 1.139; CI 1.065 to 1.219; P < 0.0001). CA risk was likewise elevated in R/HYST with number of chronic conditions. Being African American significantly decreased CA risk in R/PROST and in R/HYST or L/HYST. CONCLUSIONS: L/HYST increased CA nearly four-fold, and R/HYST approximately 6.5-fold versus O/HYST. Identifiable preoperative factors are associated with either increased risk (age, chronic conditions) or decreased risk (race).