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Results for “Surrogate variables analysis”

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PubMed2000

Linear and nonlinear time series analysis of the black hole candidate cygnus X-1

We analyze the variability in the x-ray lightcurves of the black hole candidate Cygnus X-1 by linear and nonlinear time series analysis methods. While a linear model describes the overall second order properties of the observed data well, surrogate data analysis reveals a significant deviation from linearity. We discuss the relation between shot noise models usually applied to analyze these data and linear stochastic autoregressive models. We debate statistical and interpretational issues of surrogate data testing for the present context. Finally, we suggest a combination of tools from linear and nonlinear time series analysis methods as a procedure to test the predictions of astrophysical models on observed data.

Journal Article↗

PubMed1997

Soluble vascular cell adhesion molecule-1 as a biohumoral correlate of atherosclerosis.

Vascular cell adhesion molecule-1 (VCAM-1) is a protein expressed on the surface of activated endothelial cells and expressed in early atherosclerosis. Because part of the protein is shed in the circulation and can be detected in peripheral plasma [soluble (s) VCAM-1], we hypothesized that sVCAM-1 may be a circulating marker of the presence and severity of atherosclerosis in humans. We selected 11 patients with essential hypertension plus peripheral vascular disease (PVD) and matched them for age, gender, body mass index, and smoking habits with 11 patients with uncomplicated essential hypertension (UH) and 11 healthy controls. We evaluated plasma concentrations of sVCAM-1 along with those of the soluble form of two other endothelial leukocyte adhesion molecules [sE-selectin and s-intercellular adhesion molecule-1 (sICAM-1)] and other markers of endothelial dysfunction/ damage [s-thrombomodulin, plasminogen activator inhibitor type I, and von Willebrand factor (vWF)]. We also measured insulin, glucose, fibrinogen, total and HDL cholesterol, and the urinary albumin excretion (UAE), which may also be related to atherosclerosis. Results of these assays were related to the echographic assessment of the maximum intima-media thickness (IMTmax) at the carotid bifurcation, as an index of atherosclerosis in the carotids. PVD patients had a clearly elevated IMTmax [2.7 (1.1-3.1) mm, median (range)] compared with both UH patients [1.2 (0.8-2.4) mm] and controls [1 (0.6-2) mm]. sVCAM-1 was clearly higher in PVD patients [990 (273-1808) ng/mL, median (range)] versus 340 (236-975) ng/mL in UH and 386 (204-835) ng/mL in controls, and it separated clinical categories better than sICAM-1, vWF, glucose, insulin, UAE, triglycerides, or total, LDL or HDL cholesterol, sVCAM-1 was also the best biohumoral correlate of IMTmax (R = .59; P < .001) in univariate analysis. Because many of the biohumoral variables assessed were mutually intercorrelated, they were entered in a multivariate analysis to assess their contribution in explaining IMTmax variability. sVCAM-1 remained the only independent predictor of IMTmax and totally abolished the contribution of other variables to IMTmax variability. Thus, sVCAM-1 is a good biohumoral correlate of overt atherosclerosis, independent of underlying hypertension, and may be an in vivo marker of endothelial activation. Its potential value as a surrogate for global risk assessment and its behavior in intervention studies remain to be determined.

Aged↗

PubMed2006

Elevated circulating levels of matrix metalloproteinase-9 in type 1 diabetic patients with and without retinopathy.

OBJECTIVE: Tissue expression pattern of matrix metalloproteinases (MMPs) and their inhibitors TIMPs indicate that microvascular complications of diabetes mellitus are associated with extracellular matrix remodelling. We investigated whether circulating levels of MMP-9 and TIMP-1 are altered in diabetic retinopathy and whether they might serve as biological markers of ocular complications in type 1 diabetes. RESEARCH DESIGN AND METHODS: We recruited 47 type 1 diabetic patients free of vascular complications (n=40) or with retinopathy (n=14). Patients with macroangiopathy, neuropathy and nephropathy were excluded. A group of nondiabetic control subjects (n=35) was also constituted for comparative purposes. Peripheral blood levels of MMP-9 and TIMP-1 were determined using immunoenzymatic assays. RESULTS: Type 1 diabetic subjects exhibited significantly higher circulating levels of both MMP-9 and MMP-9/TIMP-1 ratio, as well as a tendency to increased serum TIMP-1 levels relative to nondiabetic controls (p<0.001). Diabetic patients with retinopathy also displayed elevated systemic values of MMP-9 and MMP-9/TIMP-1 ratio when compared to patients without retinopathy (p<0.05). Logistic regression analysis identified diabetes duration firstly (P<0.01), and MMP-9 serum levels secondly (P<0.01) as significant and independent variables associated with the existence of retinopathy. CONCLUSIONS: Our data suggest that peripheral blood MMP-9 levels might serve as surrogate biomarkers of retinopathy in type 1 diabetic patients free of other vascular complications.

Adult↗

PubMedDate not supplied

Diesel particulate matter exposure to railroad train crews.

Exposure assessments were conducted aboard diesel locomotives. Results were evaluated to determine variables that affect exposure to DPM (diesel particulate matter) and to assess use of EC (elemental carbon) and OC (organic carbon) as surrogates for DPM. National Institute for Occupational Safety and Health Method 5040 was used for collection and analysis of samples in locomotives and in nonrailroad settings. The level of EC, but not OC, in locomotives was found to be significantly affected by position of exhaust stacks and windows. EC ranged from < 1 to 45 micrograms/m3 with a geometric mean (GM) of 3.7 micrograms/m3 and OC ranged from 4 to 4570 micrograms/m3 with a GM of 36.3 micrograms/m3. Background measurements of EC ranged from < 1 to 8 micrograms/m3 and OC levels were 4 to 84 micrograms/m3. This study confirms that train crew exposure to DPM is much lower than exposures for miners, is comparable to background urban exposures, and is lower than but comparable to exposures for truck drivers. It also indicates that EC levels are highly predictive of diesel exhaust exposure whereas OC levels are not, and that open windows and exhaust stack(s) in front of the locomotive cab have a significant effect on EC.

Air Pollutants, Occupational↗

PubMed1987

Lack of demonstrable density-dependent fecundity of schistosomiasis mansoni: analyses of Egyptian quantitative human autopsies.

Conflicting interpretations regarding the fecundity of schistosomes infecting human beings have arisen and are, in part, due to the inability to directly measure the parameters. The inability to experimentally manipulate human beings necessitates the use of surrogate variables, i.e., number of eggs per gram of feces, as an indicator of worm burden. This study reanalyzes data from quantitative autopsies performed in Egypt by Cheever and colleagues on individuals with active Schistosoma mansoni infections. Exploratory regression analysis of the relationship of female worms recovered to eggs/g of feces and of female worms to eggs retained in host tissues suggests a linear relationship in both cases. Over the observed range of female worms recovered from an individual human being, the estimated worm fecundity, as measured by the number of eggs either in feces or retained in tissues per female worm, is not significantly different from a constant value. Hence, density-dependent fecundity of S. mansoni in the human host, as suggested by others, is not demonstrated in these data.

Adolescent↗

PubMed1995

Prostate specific antigen density is not an independent predictor of response for prostate cancer treated by conformal radiotherapy.

Although prostate specific antigen (PSA) density appears to be an important discriminator between benign and malignant prostatic disease, conflicting data exist concerning its prognostic value. The present study was undertaken to confirm whether PSA density represents a new prognostic indicator of disease-free survival for prostate cancer treated with conformal radio-therapy. Between April 1989 and December 1992, 186 patients with organ confined prostate cancer were treated with definitive irradiation according to previously published conformal guidelines. The PSA density was defined as the ratio of the pretreatment serum PSA (ng./ml.) to the prostate volume (ml.) as determined from treatment planning computerized tomography. The median PSA density was 0.15 with a range of 0.02 to 2.12. A statistically significant advantage in actuarial freedom from biochemical relapse was noted for patients with pretreatment PSA levels less than 15 ng./ml. when compared to those with higher pretreatment PSA levels (3-year freedom from biochemical relapse 85% versus 28%, p < 0.001). Also, patients with PSA density of 0.15 or less had statistically superior freedom from biochemical relapse compared to their counterparts with higher PSA density (3-year freedom from biochemical relapse 88% versus 28%, p < 0.001). In a multivariate analysis only the baseline PSA (p < 0.002) and the Gleason score (p < 0.002) emerged as significant predictors of prolonged freedom from biochemical relapse. The PSA density had no impact on freedom from biochemical relapse whether it was entered into this multivariate model as a continuous or a dichotomous variable. In our data base baseline PSA levels remain the most powerful independent discriminant of response to conformal irradiation. PSA density is only a surrogate for baseline PSA levels and does not refine the ability to predict prolongation of freedom from biochemical relapse following conformal radiotherapy.

Actuarial Analysis↗

PubMed1995

Modeling long-term average exposure in occupational exposure-response analysis.

OBJECTIVES: Estimates of long-term average exposure to occupational hazards are often imprecise because intraindividual variability in exposure can be large and exposure is usually based on one or few measurements. One potential result is bias of exposure-response relationships. The possibility was studied of a more valid measure of exposure being obtained by modeling exposure and consequently increasing the number of days with exposure estimates, using simple measurable exposure surrogates. METHODS: In a group of 198 Dutch pig farmers, exposure to endotoxins was measured on one workday in summer and one day in winter. Farmers recorded activity patterns during one week in both seasons, and farm characteristics were evaluated. Relationships between farm characteristics and activities and log-transformed measured exposure levels were quantified in a multiple regression analysis. Exposure was estimated for 14 d with known activity patterns. RESULTS: The ratio of intraindividual and interindividual variance in log-transformed measured exposure was 4.7. Given this ratio, the true regression coefficient of lung function on exposure would potentially be attenuated by 70%. The variance ratio for predicted exposures was only 1.2, and the potential attenuation by variation in exposure estimates was decreased to 8%. There was no relationship between lung function and measured exposure. Modeled long-term average exposure was inversely related to base-line lung function; it reached statistical significance for asymptomatic farmers. CONCLUSIONS: The results suggest that the presented strategy offers a possibility to minimize measurement effort in occupational epidemiologic studies, without apparent loss of statistical power.

Adult↗

PubMed2001

Analysis of clonal B-cell CD38 and immunoglobulin variable region sequence status in relation to clinical outcome for B-chronic lymphocytic leukaemia.

Recent reports suggest that the expression of germline (GL) Ig variable region heavy-chain genes (VH) is a negative prognostic factor for B-cell chronic lymphocytic leukaemia (B-CLL) patients and that CLL B-cell CD38 expression may be a surrogate marker of Ig VH gene status. Currently, however, the usefulness of this surrogate marker is controversial. Therefore, our goal was to study the ability of CD38 to act as a surrogate marker for Ig VH somatic mutation (SM), and to identify differences in overall survival (OS), progression-free survival (PFS) and response in B-CLL patients based on these two markers. We first assessed the relationship between CD38 expression and Ig VH status on 131 B-CLL patients, including 66 patients enrolled in three North Central Cancer Treatment Group Trials. Although the mean percentages of CD38+ clonal B cells were significantly higher for patients classified as GL versus SM, CD38 was not a reliable marker for clonal B-cell SM. Overall, GL patients exhibited significantly shorter OS and PFS times than SM patients. Despite the inability of clonal B-cell CD38 expression to predict Ig VH mutation status, patients with < or =30% CD38+ cells did have shorter PFS and OS times than did CLL patients with < 30% CD38+ cells. Thus, the relationship between CD38 expression and Ig VH mutation status in B-CLL is not straightforward. Nevertheless, analysis in a co-operative group clinical trial setting suggests that both B-cell markers alone or in combination may have clinical usefulness. These data strongly encourage the study of these biological markers as they relate to disease heterogeneity in B-CLL.

ADP-ribosyl Cyclase↗

PubMed1981

Correlates of syntactic abilities in hearing-impaired students.

Total scores on the recently developed Screening Test from the Test of Syntactic Abilities for 382 hearing-impaired subjects between eight and 19 years and in various educational programs were found to be significantly related to hearing threshold level, number of multiple handicaps, age, educational setting, method of communication, and hearing aid usage. Multivariate analysis of variance on the effect of age controlled for hearing loss showed no significant increase in scores after eleven years of age, thus lending support to the thesis that the capacity to acquire language may cease to function at about puberty. The results of stepwise multiple regression analyses showed that, when personal variables were first forced to enter the equation, degree of hearing loss, multiple handicaps, and age accounted for 14%, nine %, an four % of the explained variability, respectively. Over and above these contributions, two manipulable variables--educational setting (a surrogate for integration) and method of communication--added significantly a further 12% and three % to the explained variability in syntactic ability.

Adolescent↗

PubMed2001

Predicting secondary progression in relapsing-remitting multiple sclerosis: a Bayesian analysis.

With the aid of a Bayesian statistical model of the natural course of relapsing remitting Multiple Sclerosis (MS), we identify short-term clinical predictors of long-term evolution of the disease, with particular focus on predicting onset of secondary progressive course (failure event) on the basis of patient information available at an early stage of disease. The model specifies the full joint probability distribution for a set of variables including early indicator variables (observed during the early stage of disease), intermediate indicator variables (observed throughout the course of disease, prefailure) and the time to failure. Our model treats the intermediate indicators as a surrogate response event, so that in right-censored patients, these indicators provide supplementary information pointing towards the unobserved failure times. Moreover, the full probability modelling approach allows the considerable uncertainty which affects certain early indicators, such as the early relapse rates, to be incorporated in the analysis. With such a model, the ability of early indicators to predict failure can be assessed more accurately and reliably, and explained in terms of the relationship between early and intermediate indicators. Moreover, a model with the aforementioned features allows us to characterize the pattern of disease course in high-risk patients, and to identify short-term manifestations which are strongly related to long-term evolution of disease, as potential surrogate responses in clinical trials. Our analysis is based on longitudinal data from 186 MS patients with a relapsing-remitting initial course. The following important early predictors of the time to progression emerged: age; number of neurological functional systems (FSs) involved; sphincter, or motor, or motor-sensory symptoms; presence of sequelae after onset. During the first 3 years of follow up, to reach EDSS> or =4 outside relapse, to have sphincter or motor relapses and to reach moderate pyramidal involvement were also found to be unfavourable prognostic factors.

Age of Onset↗

PubMed2004

Identification of candidate antigens for serologic detection of Helicobacter pylori-infected patients with gastric carcinoma.

Helicobacter pylori colonizes the stomach of almost half the world population and is a causative agent of gastric carcinomas and duodenal ulcers. Only a small fraction of infected people will develop these severe illnesses and a predictive test to identify people at high risk would greatly benefit disease management. Our study aimed to identify conserved bacterial antigens that may be useful for the development of such a diagnostic test. High-resolution immunoproteomics by 2-dimensional electrophoresis of H. pylori 26695 proteins was carried out with sera from infected patients with either duodenal ulcer (n=30) or gastric carcinoma (n=30), 2 clinically divergent conditions. According to their antigen recognition patterns clear groups of patients were identified. Although this classification did not correspond to the clinical status, it may be correlated to other bacterial or host factors that influence the outcome of infection. In general antigen recognition patterns were found to be highly variable, however by utilizing powerful image analysis and statistical tests the recognition of 14 antigenic protein species was found to differ significantly (p<0.01) between both diseases. Particular protein species of GroEL, HyuA, GroES and AtpA appear to be useful surrogate markers for gastric carcinoma detection and consequently should be considered for further prospective studies to assess their predictive value. For one protein species of AtpA, evidence was found that different post-translational modifications may confer different immunogenicities.

Adenocarcinoma↗

PubMed2001

Case-cohort analysis of agricultural pesticide applications near maternal residence and selected causes of fetal death.

The potential association between fetal death and residential proximity to agricultural pesticide applications was examined in 10 California counties for 1984. A case-cohort analysis utilized 319 cases of selected causes of fetal death other than congenital anomalies and 611 non-cases. A statewide database of all applications of restricted pesticides was linked to maternal address; residential proximity within 1 mile (1.6 km) provided a surrogate for daily exposure. Pesticides were grouped by chemical class and mechanism of acetylcholinesterase inhibition. Multivariate proportional hazards models using time-dependent exposure variables were fit for each pesticide grouping. Overall, pesticides showed no strong association with fetal death. Slightly elevated risks were observed for women who resided near applications of halogenated hydrocarbons, carbamates, estrogenic pesticides, and carbamate acetylcholinesterase inhibitors during the second trimester, with hazard ratios of 1.3 (95% confidence interval (CI): 1.0, 1.8), 1.3 (95% CI: 1.0, 1.8), 1.4 (95% CI: 0.8, 2.5), and 1.3 (95% CI: 1.0, 1.8), respectively. In a month-by-month analysis, elevated risks were observed when exposure occurred during gestational months 3 and 4 for carbamates and carbamate inhibitors and during months 4 and 5 for halogenated hydrocarbons. Since previous studies have relied on personal recall of exposure, major strengths of this study were the objective source for environmental pesticide exposure assessment and the use of data on the timing of exposure.

California↗

PubMed2005

Temporal analysis of airborne particulate matter reveals a dose-rate effect on mortality in El Paso: indications of differential toxicity for different particle mixtures.

One of two topics explored is the limitations of the daily average in summarizing pollutant hourly profiles. The daily average of hourly measurements of air pollutant constituents provides continuity with previous studies using monitoring technology that only provided the daily average. However, other summary statistics are needed that make better use of all available information in 24-hr profiles. The daily average reflects the total daily dose, obscuring hourly resolution of the dose rate. Air pollutant exposures with comparable total daily doses may have very different effects when occurring at high levels over a few hours as opposed to low levels over a longer time. Alternative data-based choices for summary statistics are provided using principal component analysis to capture the exposure dose rate, while preserving ease of interpretation. This is demonstrated using the earliest hourly particle concentration data available for El Paso from archived records of particulate matter (PM)10. In this way, a significant association between evening PM10 exposures and nonaccidental daily mortality is found in El Paso from 1992 to 1995, otherwise missed using the daily average. Secondly, the nature and, hence, effects of particles in the ambient aerosol during El Paso sandstorms is believed different from that of particles present during still-air conditions resulting from atmospheric temperature inversions. To investigate this, wind speed (ws) is used as a surrogate variable to label PM10 exposures as Low-ws (primarily fine particles), High-ws (primarily coarse particles), or Mid-ws (a mixture of fine and coarse particles). A High-ws evening is significantly associated with a 10% lower risk of mortality on the succeeding third day, as compared with comparable exposures at Low- or Mid-ws. Although this analysis cannot be used to form firm conclusions because it uses a very small data set, it demonstrates the limitations of the daily average and suggests differential toxicity for different particle compositions.

Air Pollutants↗

PubMed1981

Engaging "resistant" families in treatment.

Many families, when presented with the option of family therapy, are less than eager to participate. This paper comprises the second and third parts of a series on engaging "resistant" families. Part II presents 21 principles and a number of techniques and strategies that have been developed for successfully recruiting such families. These techniques should be applicable for engaging resistant families with all types of presenting problems. Part III provides an analysis of the important variables involved, along with data on cost efficiency and administrative costs. It was found that when therapists had administrative control of their cases, serving in dual roles as both therapists and drug counselors, the recruitment effort was (a) more effective (i.e., complete families, including both parents or parent surrogates, were recruited in 77 per cent of the cases), and (b) twice as cost efficient. Two-thirds of the non-engaged families were not recruited because the index patient would not allow family members to be contacted. Black families were more difficult to recruit than whites. Data on cost efficiency and on the actual administrative costs of recruiting families are also provided.

Adult↗

PubMed2001

Time- and frequency-domain estimation of early diabetic cardiovascular autonomic neuropathy.

The risk related to cardiovascular autonomic neuropathy dysautonomia should lead to a specific assessment of this complication of diabetes. The aim of this study was to estimate the accuracy of a battery of blood pressure (BP) and heart rate (HR) variability indexes obtained in different subgroups of diabetic subjects classified according to the conventional laboratory autonomic function tests (Ewing scores). Blood pressure was measured continuously at the finger level with a Finapres monitor while subjects were in the supine position and again while they were standing. Pulse intervals were derived from BP recordings and were taken as surrogates for R-R intervals. Subjects with borderline or definite cardiovascular autonomic neuropathy showed a similar degree of alterations of both HR and BP variability (spectral measures) and in the relationship between BP and HR (cross-spectral and sequence analysis). Subjects with no evidence of cardiovascular autonomic neuropathy on the basis of the conventional tests showed an altered relationship between BP and HR. This baroreceptor-HR reflex dysfunction could represent an early stage of cardiovascular autonomic neuropathy undetected by the conventional tests. The areas under the receiver operating characteristic plots indicated that the high-frequency peak of pulse interval was highly discriminant in the supine and standing positions. The cross-spectral analysis showed the best discrimination for the gain in the high-frequency range. For the sequence analysis, the slope was the best discriminant factor for any degree of cardiovascular autonomic neuropathy. In conclusion, these estimates of baroreceptor-HR function may provide a powerful tool for assessing cardiovascular autonomic neuropathy at any stage, including the early stage, which is not detected by the conventional tests.

Adult↗

PubMedDate not supplied

Quantitative image analysis of oesophageal squamous cell carcinoma from the high-incidence area of China, with special reference to tumour progression and papillomavirus (HPV) involvement.

BACKGROUND: Despite much research effort, the major prognostic factor of oesophageal squamous cell cancer (ESCC) remains the pathological stage of the disease as defined by the TNM classification, whereas tumour grading is of limited value in this respect, mainly due to its low reproducibility. A better means for disease prognostication based on improved understanding of the pathogenetic mechanisms is urgently required. MATERIALS AND METHODS: Among the cohort of 700 ESCC patients from the high-incidence area of China, previously subjected to extensive testing for Human papillomavirus (HPV) involvement by in situ hybridization (ISH) and PCR, a group of 273 patients was randomly selected for analysis of the primary tumour, adjacent mucosa and regional lymph nodes, by histopathology and quantitative image analysis. All these and the HPV data were subjected to extensive univariate and multivariate analysis to disclose independent predictors of progressive disease. RESULTS: For the analyses, the tumours were graded into two categories: well-moderately and poorly-differentiated. HPV DNA was detected in 116 (18.9%) of the carcinomas by ISH and in 15.2% by PCR. In univariate analysis, lymph node status (considered as the surrogate marker of progressive disease) was significantly (p < 0.01) predicted by the following nuclear parameters: nuclear area, G0/G1 ratio, HPV DNA status, integrated optical density (IOD), mean optical density (MOD) and S-Phase. In multivariate (stepwise backward LR) analysis, 6 variables remained as independent predictors of disease progression (at p < 0.05 level), the three most significant ones being nuclear perimeter, nuclear roundness and equivalent diameter (p < 0.01). CONCLUSION: A series of quantitatively measured nuclear parameters seem to bear a close correlation with ESCC differentiation and progression in univariate analysis and some of these variables proved to be significant independent predictors of disease progression in multivariate modelling as well. These data clearly advocate the use of quantitative image analysis in searching for additional prognostic factors of ESCC.

Carcinoma, Squamous Cell↗

PubMed2005

Nonlinear analyses of heart rate variability in normal and growth-restricted fetuses.

BACKGROUND: Many studies on the physiology of the cardiovascular system reported that nonlinear chaotic dynamics may govern the generation of the heart rate signal. OBJECTIVE: To examine whether the heart rate dynamics of an intrauterine growth restricted (IUGR) fetus is different from a healthy normal fetus by nonlinear methods of time series analysis. DESIGN OF THE STUDY: One hundred nineteen fetal heart rate (FHR) recordings from healthy normal fetuses, and 69 recordings from IUGR fetuses were analyzed. Nonlinear analyses included attractor reconstruction, calculation of the largest Lyapunov exponents using the Wolf algorithm, and estimation of correlation dimension. The largest Lyapunov exponents from normal fetuses were checked by means of surrogate-data test. RESULTS: Abnormal FHR patterns of IUGR fetuses such as decreased variability and repetitive late decelerations presented a remarkably different structure in the reconstructed attractor. Surrogate data suggest that the FHR of healthy normal fetuses has unique nonlinear characteristics. The largest Lyapunov exponents were positive for all of 119 healthy normal fetuses, indicating that the FHR control system is sensitive to initial conditions. The values of IUGR fetuses were significantly lower than those of normal subjects. In normal fetuses, significant changes of correlation dimension according to gestational age were observed. In IUGR fetuses, however, such changes were not found. CONCLUSIONS: The heart rate dynamics of IUGR fetuses is less chaotic than that of normal fetuses. Decreased system complexity suggested by correlation dimension may limit the IUGR fetuses' ability to maintain cardiovascular integrity, and therefore, to adapt to the variety of internal and external cardiovascular stresses.

Female↗

PubMed2006

Oocyte degeneration after intracytoplasmic sperm injection: a multivariate analysis to assess its importance as a laboratory or clinical marker.

OBJECTIVE: Oocyte degeneration has historically been associated with the intracytoplasmic (ICSI) technique. We sought to determine whether oocyte degeneration rates were associated with the technician performing the procedure, the baseline characteristics of the patient, and/or ovarian stimulation variables. We also evaluated whether the degeneration rate could serve as a surrogate marker for implantation potential. DESIGN: Cohort study. SETTING: Academic medical center. PATIENT(S): Couples undergoing ICSI. INTERVENTION(S): Six thousand six hundred fifty-three injected oocytes were analyzed to determine whether the degeneration rate was technician dependent. Two hundred thirty first-entry down-regulated cycles were examined to identify predictors associated with oocyte degeneration. Multivariate analyses were performed using generalized linear model routines. MAIN OUTCOME MEASURE(S): Oocyte degeneration rates and implantation rates. RESULT(S): Neither the ICSI technician nor the stripping technician was associated with the oocyte degeneration rate. However, the day 3 FSH, number of mature oocytes retrieved, and E2 levels on the day of hCG were significant independent predictors of degeneration rate. Physician-adjustable ovarian stimulation variables were not associated with the degeneration rate. The degeneration rate did not appear to be associated with the implantation rate. CONCLUSION(S): These data suggest that oocyte degeneration is not technician or physician dependent. Degeneration is likely a function of the inherent oocyte quality in women who underwent ovarian stimulation. However, the remaining cohort of retrieved oocytes appears to be unaffected by virtue of an uncompromised implantation rate.

Adult↗