Generalized empirical likelihood testing in semiparametric conditional moment restrictions models

Summary This paper shows how generalized empirical likelihood can be used to obtain specification tests in semiparametric conditional moment restrictions models. The resulting test statistics are similar in spirit to classical Kolmogorov–Smirnov and Cramer von Mises goodness‐of‐fit statistics and are based on an integrated version of the original moment restrictions. The results are applied to test the correct specification of an instrumental variable smooth varying coefficient model and of a censored non‐linear quantile regression model. Monte Carlo results suggest that the proposed tests have competitive finite sample properties.     

HCV seroconversion among never-injecting heroin users at baseline: No predictors identified other than starting injection

BACKGROUND: Heroin users who do not inject constitute a large pool of drug users with a potentially important impact on public health. We aimed to estimate the incidence of hepatitis C virus (HCV) among heroin users who had never injected (NIDUS) at baseline, and the effect of starting injecting during follow-up, other percutaneous exposures, sharing snorting paraphernalia, cocaine/crack use, and risky sexual behaviour on HCV-seroconversion. METHODS: Prospective cohort of 305 HCV-negative NIDUs at baseline, aged 18-30 and street-recruited in three Spanish cities in 2001-2003. Computer-assisted personal interviews were conducted and dried blood-spot samples were collected. Bivariate and multivariable Poisson models were used. RESULTS: Among the 305 never-injectors who were HCV-negative at baseline, 197 (64.6%) were followed-up and 21 seroconverted [HCV-incidence rate=5.8/100 person-years at risk (pyar) (95% CI: 3.6-8.9)]. HCV incidence in new-injectors was 28.4/100pyar [(95% CI, 14.7-49.7) vs. 2.8/100pyar (95% CI, 1.3-5.4)] among NIDUs. Of the risk exposures considered, starting injecting was the only predictor of HCV-seroconversion [adjusted relative risk=10.1, 95% CI: 3.8-26.7]. CONCLUSION: The HCV-seroconversion rate was 10 times higher among new-injectors than never-injectors. No predictors other than starting injecting were found for HCV-seroconversion. Harm reduction interventions to prevent HCV infection should include prevention of drug injection.     

Vascular and adrenocortical responses to a specific antagonist of angiotensin II.

Angiotensin II receptors in vascular smooth muscle and adrenal cortex have been characterized in the dog. The evidence was derived chiefly from experiments that assessed the ability of a structural analog of angiotensin II, [Sar1, Ile8] AII, to antagonize the effects of exogenously administered angiotensin II on arterial pressure and aldosterone secretion. [Sar1, Ile8] AII is a potent and specific blocker of the pressor response to angiotensinII; in the adrenal cortex, it is a much less effective inhibitor of aldosterone biosynthesis. These results indicate differences in the receptor sites for angiotensin II in vascular smooth muscle and adrenal cortex. Further, they raise the possibility that angiotensin II stimulates aldosterone secretion by mechanisms other than have already been proposed.     

Predictors of handicap situations following post-stroke rehabilitation

Purpose : Many stroke survivors have to cope with impairments and disabilities that may result in the occurrence of handicap situations. The purpose of the study was to explore bio-psycho-social predictors of handicap situations six months after discharge from an intensive rehabilitation programme. Methods : At discharge from a rehabilitation programme, participants were evaluated with instruments measuring motor, sensory, cognitive, perceptual, affective and psychosocial impairments and disabilities that may play a role in the development of handicap. Some other demographic and clinical variables, and those related to rehabilitation, were also collected. Six months later, they were re-assessed in their own environment in order to document their handicap level with the Assessment of Life Habits (LIFE-H). Results : One hundred and thirty-two stroke patients participated in the discharge evaluation and 102 of them also participated in the handicap measurement. Relationships between handicap level and impairments and disabilities were all statistically significant. Multiple regression analyses indicated that affect, lower extremity co-ordination, length of stay in rehabilitation, balance, age and comorbidity at the end of an intensive rehabilitation programme are the best predictors of handicap situations six months later (adjusted R 2 : 68.1%). Conclusions : In spite of its exploratory nature, this study revealed that, among a substantial number of personal characteristics, some were more related to a handicap measure and have greater predictive value. Other studies should be carried out to validate these findings and to consider more environmental factors in order to better understand factors related to the development of handicap situations.     

Laparoscopic-assisted approach in rectal cancer patients: lessons learned from >200 patients

Background The applicability of laparoscopic surgery in the treatment of colorectal diseases is still controversial. Early reports on laparoscopic-assisted colectomy in patients with colon cancer suggested that it minimizes surgical trauma, decreases perioperative complications, and leads to a more rapid recovery. To our knowledge, no previous studies have compared the laparoscopic vs the open approach in rectal cancer. The aim of this paper was to assess the results of laparoscopic techniques in patients with rectal cancer.Methods From March 1998 to February 2003, all patients admitted to our unit with adenocarcinoma of the rectum were evaluated for surgery by the laparoscopic approach.Results A total of 220 patients with a mean age of 67.3 years were included in the study. One hundred thirty patients (59%) were treated with neoadjuvant chemoradiotherapy. In >75% of the patients, a surgical procedure with sphincter preservation was perfomed. The rate of conversion to the open approach was 20%. Ten patients had intraoperative complications. Fifty-eight patients (26.3%) developed postoperative complications. The length of hospital stay was 6.8 days. The distribution of tumor stages was as follows: stage I, 16.81%; stage II, 33.6%; stage III, 26.36%; stage IV, 19.09%. The mean number of lymph nodes was 13.8. The incidence of local relapse was 5.3%, with a follow-up of 18 months.Conclusion Laparoscopic surgery can be safely performed in patients with adenocarcinoma of the rectum with good short-term results. Randomized controlled trials are needed to confirm these results.     

Incidence of and Risk Factors for Screw Loosening after Iliosacral Screw Fixation for Posterior Pelvic Ring Injury

Purposes

Screw loosening is a common complication of iliosacral screw fixation, with subsequent loss of stability and fracture re-displacement. This study aimed to investigate the incidence of and risk factors for screw loosening after iliosacral screw fixation for posterior pelvic ring injury.

Methods

A total of 135 patients with posterior pelvic ring injuries who were treated with iliosacral screw fixation in our department between July 2015 and April 2021 were selected for this retrospective analysis. The possible risk factors for screw loosening were investigated using univariate and multivariate logistic regression analyses of patient demographics and trauma-related and iatrogenic variables, including age, sex, body mass index, Osteoporosis Self-Assessment Tool for Asians (OSTA) index, mechanism of injury, Young–Burgess classification, site of injury, type of injury, type of screw, mode of fixation, numbers of guidewire adjustments, accuracy of screw position, and quality of fracture reduction.

Results

The incidence of screw loosening was 15.6% (n = 21). The mean duration for screw loosening was 3.2 ± 1.5 months after operation. Univariate analysis results showed that the Young–Burgess classification, type of injury, site of injury, type of screw, mode of fixation, and OSTA index might be related to screw loosening (p < 0.05). According to the multivariate logistic regression, vertical shear injuries (Odds ratios [OR] 9.80, 95% Confidence intervals [CI] [1.96–73.28], p = 0.008), type of injury (OR 0.25, 95% CI [0.13–0.79], p = 0.027), common screws (OR 6.94, 95% CI [1.53–31.40], p = 0.012), screws insertion only at the level of the first sacral segment (S1) (OR 8.79, 95% CI [1.18–65.46], p = 0.034), injury site located in the medial sacral foramina (OR 6.28, 95% CI [1.16–34.06], p = 0.033), and lower OSTA index [OR 0.41, 95% CI [0.24–0.71], p = 0.001] were significantly related to screw loosening.

Conclusions

Vertical shear injuries, sacral fractures, injury site located in the medial sacral foramina, and lower OSTA index are significantly associated with the postoperative occurrence of screw loosening. Transiliac–transsacral screw fixation and screws insertion both at the level of the S1 and second sacral segment can prevent screw loosening.