Biomedical subjects

R Ecochard

Publications and source records attributed to R Ecochard.

At least 37 records · Page 2Linked to original sources

PubMed2001

Planned vaginal delivery versus elective caesarean section in singleton term breech presentation: a study of 1116 cases.

OBJECTIVE: To compare neonatal and maternal morbidity and mortality between planned vaginal delivery and elective cesarean section for singleton term breech presentation. STUDY DESIGN: We studied retrospectively all deliveries of singleton breech presentations at term in the public Hospitals of Lyon between 1 January 1991 and 31 December 1995. To take only the effect of delivery on the fetus into account, we eliminated high risk pregnancies and fetal malformations. Fetal parameters were corrected perinatal mortality, Apgar score<7 at 1 and 5 min, umbilical cord arterial pH<7.15, neurological disorders, trauma and need for neonatal intensive care. Maternal parameters were mild, moderate and severe complications. RESULTS: Of the 1116 breech presentations, 702 (62.9%) underwent an elective caesarean section and 414 (37.1%) a planned vaginal delivery. In the latter group, 342 (30.6%) had a vaginal delivery and 72 (6.5%) a non-elective caesarean section. Infants for whom the vaginal route was planned were at higher risk of mortality and morbidity. There were 2 deaths in this group and none in the elective caesarean section group and all fetal parameters were poorer: more Apgar<7 at 5 min (RR: relative risk=3.05; 1.03-9.05), arterial pH<7.15 (RR=1.64; 1.11-2.43), intubations (RR=7.35; 2.10-25.6), neurological disorders, trauma (RR=4.24; 1.66-10.8), transfer to intensive care units (RR=3.23; 1.57-6.64). The overall maternal morbidity was lower in the planned vaginal delivery group (RR=0.65; 0.44-0.94) but this was only because of less mild complications. The moderate and severe complications were the same in the two groups (RR=0.97; 0.59-1.57). CONCLUSIONS: Planned vaginal delivery in singleton term breech presentation increases the risk of death and of neonatal complications. Elective caesarean section increases the risk of only mild maternal complications. For these reasons, elective caesarean section should be preferred for singleton term breech presentations.

Adult↗

PubMed2001

Total-body-water measurement with (18)O-labeled water in short-bowel patients with an ileostomy.

The aim of this study was to evaluate the use of H(2)(18)O for total-body-water (TBW) determination in patients with short bowel because ileostomy losses of labeled water can falsify TBW. Thirteen adult short-bowel patients were studied after an overnight fast. Saliva, blood, urine and ileostomy output were collected before and 30, 60, 90, 120, 240, and 360 min after oral ingestion of 0.88 g/kg of 2.5% H(2)(18)O to measure (18)O abundance by isotope-ratio mass spectrometry. TBW was calculated from the dilution of the isotopic water in saliva and plasma. The quantity of labeled water lost in the ileostomy was calculated from the isotopic enrichment of the ileostomy output from T0 to T360. The values obtained from saliva or plasma with (corrected) and without (uncorrected) considering H(2)(18)O lost in the ileostomy output were compared with a paired t test. Agreement was evaluated using the Bland-Altman method. From T0 to T360, the ileostomy output and the percentage of lost labeled water were 490 +/- 314 mL and 6.38 +/- 8.52%, respectively. TBW calculated from plasma or saliva isotopic enrichment was different, and a significant difference was also observed between corrected and uncorrected TBW values (saliva: uncorrected TBW = 32.35 +/- 7.52 L, corrected TBW = 30.29 +/- 6.09 L; plasma; uncorrected TBW = 30.80 +/- 7.29 L, corrected TBW = 28.79 +/- 5.79 L). The agreement between the values obtained from the two dilution spaces or between the two calculation methods was poor. Because of the large discrepancies between calculation methods, determination of TBW from oral ingestion of (18)O-labeled water in patients with short bowel should be calculated only from plasma (18)O space dilution and should consider ileostomy losses.

Body Water↗

PubMed2001

Worsening of heart failure during hospital course of an unselected cohort of 2507 patients with myocardial infarction is a factor of poor prognosis: the PRIMA study. Prise en charge de l'Infarctus du Myocarde Aigu.

Worsening of heart failure in patients with myocardial infarction is seldom studied, elderly patients often are not included, and multivariate analysis is uncommon. The prospective PRIMA study (Prise en charge de l'Infarctus du Myocarde Aigu; management of acute myocardial infarction) sought to determine the incidence of worsening heart failure, its risk factors, and its prognostic importance in patients with myocardial infarction, regardless of age and hospital facilities, in the 'real world' in a region in France, using multivariate analysis. Data were prospectively collected in all patients with myocardial infarction admitted in all hospitals in three departments in the Rhône--Alpes region in France between 1 September 1993 and 31 January 1995. Among the 2507 patients included, 33% were in Killip classes II--IV at admission. After exclusion of patients with admission Killip class IV, 416 patients (17% of the cohort, 24% of women and 14% of men) had worsening of Killip class during the first 5 days. In-hospital mortality (overall, 14%) increased dramatically with Killip class at admission (9% in class I, 62% in class IV) and with worsening of Killip class during the first 5 days (36.5 vs. 8.5% if no worsening). In multivariate analysis, older age, diabetes mellitus and anterior Q-wave myocardial infarction were significant predictors of Killip class at admission and of its worsening; Killip class >I at admission was a significant predictor of Killip-class worsening. The significant predictors of in-hospital mortality were older age, Killip class III at admission and worsening of Killip class during the first 5 days. This large, unselected cohort revealed that, among patients with myocardial infarction, heart failure and its worsening are frequent, especially in the elderly, and dramatically worsen the in-hospital mortality.

Aged↗

PubMed2001

Indicators of myocardial dysfunction and quality of life, one year after acute infarction.

BACKGROUND: There remains controversy concerning the association between myocardial dysfunction diagnosed soon after acute myocardial infarction (AMI), and subsequent quality of life. AIMS: We searched for a correlation between criteria of myocardial dysfunction assessed within the first month after AMI, and quality of life perceived 1 year later. METHODS: Six hundred and seventy-one patients were followed up and quality of life was assessed using the Nottingham Health Profile. Spearman correlation was used for univariate analyses. A logistic regression identified independent predictors of impaired quality of life. RESULTS: Patients perceiving inferior quality of life were 61% for energy, 61% for sleep, 49% for physical mobility, 49% for pain, 63% for emotional reactions, and 28% for social isolation. Impaired quality of life was not associated with the initial Killip class. A low ejection fraction was associated with impaired physical mobility (OR=1.21, 95% CI=1.05-1.39). Presence of abnormally contracting myocardial segments was associated with impaired mobility (1.40, 1.09-1.80) and with increased pain (1.30, 1.02-1.66). The presence of diseased coronary vessels was associated with pain (1.25, 1.06-1.46). CONCLUSION: Myocardial dysfunction was generally associated with impaired quality of life. This has to be considered when assessing improvement of quality of life after medical or surgical treatment of AMI.

Activities of Daily Living↗

PubMed2001

Impact of selected geographical and clinical conditions on thrombolysis rate in myocardial infarction in three departments of France.

Our objective was to assess the impact of selected geographic factors and patients' characteristics on thrombolysis rates in patients resident and hospitalised for acute myocardial infarction in three departments of the Rhĵne-Alpes Region (France). We used a two-level hierarchical model to estimate and explain geographic areas' specific effects. Old subjects and women were less frequently treated than young subjects and men. Severe, non-anterior and non-Q-wave myocardial infarctions were associated with lower thrombolysis rates. It was also lower in patients with a pulmonary chronic disease, a cancer, a peripheral arterial disease, a history of cerebrovascular accident or transient ischaemia attack, and in patients with a psychiatric disorder. After adjusting for patients' characteristics, significant variations in thrombolysis rates remained between geographic areas (up to 3.2 times). These variations seem to be partly explained by distance or isolation: a longer distance to the closest hospital or a high degree of isolation seem to lower the probability of thrombolytic therapy. Several other sources of treatment variation between the studied geographic areas remain unexplored. These factors, especially those that augment the delay to treatment, are to be identified in order to augment fibrinolysis usage and reduce inter-area heterogeneity.

Age Factors↗

PubMed2001

Chronological aspects of ultrasonic, hormonal, and other indirect indices of ovulation.

OBJECTIVE: To improve prediction of ovulation in normal cycles. DESIGN: Collection of women's characteristics and their menstrual cycles. Monitoring and analysis of time relationships between several indicators of ovulation: transvaginal ultrasonography, cervical mucus, basal body temperature, urinary luteinising hormone, and ratio of urinary oestrogen to progesterone metabolites. SETTING: Each of eight natural family planning clinics was to study 12 women for at least three cycles. POPULATION: One hundred and seven normally fertile and cycling women aged 18 to 45. METHODS: Daily measurements of urinary luteinising hormone, follicle stimulating hormone, oestrone-3-glucuronide and pregnanediol-3alpha-glucuronide. Basal body temperature recording and cervical mucus checking. Transvaginal ultrasound examination of the ovaries. MAIN OUTCOME MEASURES: Delays between the expected day of ovulation according to the luteinising hormone peak or to ultrasound evidence and the expected days according to the other indices of ovulation. RESULTS: Ultrasonography was able to show evidence of ovulation in 283 out of 326 cycles. The average time lag between luteinising hormone peak and ultrasound evidence was less than one day (+0.46) but premature and late luteinising hormone-expected date of ovulation were observed in nearly 10% and 23% of cycles, respectively. Basal body temperature rise was observed in 98% of cycles. Cervical mucus peak symptom, rapid drop in the ratio of urinary metabolites, and luteinising hormone initial rise were all close to ultrasonographic evidence in more than 72% of cycles. CONCLUSIONS: For accuracy and practical reasons, the cervical mucus peak symptom, the ratio of urinary metabolites and luteinising hormone initial rise might be better indices of ovulation than the luteinising hormone peak.

Adult↗

PubMed2001

Treatment at discharge after myocardial infarction in 2,102 patients. The PRIMA study. Prise en charge de l'Infarctus du Myocarde Aigu.

OBJECTIVE: This study sought to examine the use of treatments at discharge in patients hospitalized for myocardial infarction in a French region. METHODS AND RESULTS: Data from 2,102 patients discharged after myocardial infarction were prospectively collected at 48 university, community, and private hospitals in three departments in the Rh ne-Alpes region between September 1, 1993 and January 31, 1995. Beta-blockers were prescribed in 59% of the patients, calcium channel blockers in 22%, nitrates in 59%, antiplatelet agents in 82%, anticoagulants in 26%, angiotensin-converting enzyme inhibitors in 36%, diuretics in 33%. Beta-blockers were prescribed less often in older patients, and in patients with higher Killip classes or a history of pulmonary disease. Calcium channel blockers were prescribed more often in older patients, and in patients with a history of diabetes, pulmonary disease, or non-Q wave myocardial infarction. Nitrates were prescribed more often in older patients. Angiotensin-converting enzyme inhibitors were prescribed more often in patients with a history of diabetes, hypertension, or anterior myocardial infarction, and less often in patients with a history of renal failure. Diuretics were prescribed more often in older patients, and in patients with a history of renal failure, diabetes, hypertension, or higher Killip classes. CONCLUSIONS: There is still underuse of beneficial treatments, particularly in elderly patients.

Adrenergic beta-Antagonists↗

PubMed2001

Are women with acute myocardial infarction managed as well as men? Does it have consequences on in-hospital mortality? Analysis of an unselected cohort of 801 women and 1,718 men.

OBJECTIVE: This study sought to compare characteristics and management of myocardial infarction in men and women, and whether a difference in management would translate into a difference in in-hospital mortality. METHODS AND RESULTS: Data were prospectively collected in 2,519 patients (801 women) admitted in all hospitals in three departments in the Rhĵne-Alpes region in France between September 1, 1993 and January 31, 1995. Women were older than men (76 vs. 64 years). The interval between symptom onset and initial medical intervention was longer in women than in men (median: 180 vs. 135 minutes), as was the interval between symptom onset and hospital admission (median: 315 vs. 255 minutes). After age-adjustment, women were less often smokers, and more often hypertensive or diabetic than men, location of infarction was more often anterior in women, as congestive heart failure at admission. In multivariate analysis, thrombolysis rate was not significantly different in both sexes, whereas noninvasive tests, coronary arteriography, percutaneous transluminal coronary angioplasty, and coronary artery bypass grafting were significantly less often performed in women than in men. Although in-hospital mortality was higher in women than in men (21% vs. 11%), this difference disappeared after age-adjustment (relative risk = 0.99). In multivariate analysis, gender was not an independent predictor of survival. CONCLUSIONS: Although in-hospital mortality after myocardial infarction was similar in both sexes, rates of diagnostic and therapeutic procedures were lower in women than in men. This raises the question of whether mortality would decrease in women if management were similar in both sexes.

Age Factors↗

PubMed2001

Thrombolysis in myocardial infarction in a prospective cohort of 2,515 consecutive patients: older age and longer delays lead to a lower thrombolysis rate.

OBJECTIVE: This prospective study sought to determine the rate of thrombolysis in myocardial infarction and the factors that influenced it in everyday practice. METHODS AND RESULTS: Data were prospectively collected in all patients admitted in all (48) university, community, and private hospitals in three departments in the Rhĵne-Alpes region in France between September 1, 1993 and January 31, 1995. Data from 2,515 patients were included. Overall, 36% of the patients received thrombolysis. The decrease of the thrombolysis rate with age was very regular. The difference between men and women disappeared almost completely when age was taken into account in a bivariate analysis. Among 19 variables introduced in the logistic regression, only the following ones were significant predictors (odds ratio < 1 means less thrombolysis): age (odds ratio: 0.60 per decade), administrative department, type of hospital (community/tertiary: 0.74; private/tertiary: 0.58), history of myocardial infarction or of angina pectoris (0.67), location of myocardial infarction (Q wave non anterior/Q wave anterior: 0.75; non Q wave/Q wave anterior: 0.18), delay between symptoms onset and first medical intervention (0.06), history of cancer (0.47), and history of psychiatric disorder (0.38). CONCLUSIONS: In France as in other countries, the rate of thrombolysis is low. In order to increase this rate, we have to find ways to be more "aggressive" in older patients, and to precisely describe the health care pathways in order to shorten delays.

Age Distribution↗

PubMed2001

(13)CO(2) breath tests: comparison of isotope ratio mass spectrometry and non-dispersive infrared spectrometry results.

BACKGROUND AND AIMS: Isotope ratio mass spectrometry is the standard analytical method for (13)CO(2) breath tests. The goal of this study was to compare the results of (13)CO(2) breath tests obtained by non dispersive infrared spectrometry, a new, simpler and cheaper method, with those obtained by the gold standard method. METHODS: Three hundred and eight patients were included: 150 underwent a urea breath test for Helicobacter pylori diagnosis, 140 an aminopyrine breath test to measure liver function, and 18 an octanoic acid breath test for gastric emptying evaluation. A total of 750 breath samples were obtained in duplicate for isotope ratio mass and infrared spectrometry analyses. Breath test results were compared using Bland-Altman plots. RESULTS: The agreement between the two methods was excellent for urea breath tests (kappa coefficient=0.96), with only 3 discordant results. Although (13)C isotopic enrichment in breath was significantly lower with infrared spectrometry (P<0.0001), the agreement for the results of aminopyrine and octanoic acid breath tests was excellent. The clinical significance of these tests was similar for both methods. CONCLUSIONS: Infrared spectrometry results are comparable to isotope ratio mass spectrometry. Because this analytical method is simpler and less expensive, it could be used for clinical applications of (13)CO(2) breath tests.

Adolescent↗

PubMed2001

[Adrenal vein catheterization in primary hyperaldosteronism: aid in surgical decision making?].

UNLABELLED: The localisation of aldosterone-producing adenomas (APA's) remains difficult. Indeed, CT scan may not detect small APA's while CT detected tumours do not necessarily produce aldosterone. OBJECTIVE: To evaluate the value of adrenal vein catheterization (AVC) for the diagnosis of APA's and also the rates of unsuccessful procedures and complications. PATIENTS: One-hundred-and-nine hypertensives with biological features of primary hyperaldosteronism were included. Plasma sodium, potassium, aldosterone and renin levels were obtained after one night in lying position. Aldosterone and renin levels were also measured after a one-hour walking period and after a sodium expansion with saline. All patients underwent a CT scan and AVC. For adrenal samples, the ratio of aldosterone to cortisol concentrations was calculated for both sides. Both ratios were divided by the opposite one and the higher was retained as an index of laterization (IL). For lack of a golden standard variable, we have taken as a working hypothesis that operated patients had an APA (n = 38) and the non operated ones bilateral hypereplasia (n = 71). RESULTS: Operated patients had a shorter history of hypertension, more frequently a left ventricular hypertrophy on ECG, and lower serum creatinine and potassium levels, along with a higher sodium level. None of these features appeared discriminant, however. Presence of a 10-mm tumour on CT scan was not significantly different between the 2 groups. Operated patients had more than a five-fold higher IL compared with that of non-operated patients. Analysis using a ROC curve showed that the value of 12 for "IL" was an acceptable operational criterium of lateralization, producing a specificity of 90%, while maintaining a sensitivity of 62%. AVC appeared most useful in case of middle-range pre-test probability of an APA being present, that is when when clinical, biological, or radiological features are not fully concordant. The rate of unsuccessful procedure and the rate of complications were low (1.8% and 3.6%, respectively). CONCLUSION: With a low iatrogenicity, AVC appears helpful in indicating surgery mostly when clinical, biological, and CT scan features are not fully concordant. A value of 12 for IL appears to allow a high specificity while retaining an acceptable sensitivity.

Adenoma↗

PubMed2000

A randomized prospective study comparing pregnancy rates after clomiphene citrate and human menopausal gonadotropin before intrauterine insemination.

OBJECTIVE: To determine whether hMG offers an advantage over clomiphene citrate (CC) in achieving pregnancy after IUI with husband's sperm. DESIGN: Randomized prospective trial. SETTING: Infertility patients in a university teaching hospital. PATIENT(S): Fifty-eight women under 39 years old undergoing ovulation induction before IUI. INTERVENTION(S): The women were assigned randomly to one of two treatment groups. Patients in group I (CCHH) received CC for the first two cycles and hMG for the last two cycles. Patients in group II (HHCC) received hMG for the first two cycles and CC for the last two cycles. MAIN OUTCOME MEASURE(S): Cycle fecundity rates for the two treatment modalities were compared statistically with use of life-table analysis. RESULT(S): Of the 174 cycles studied, overall cycle fecundity rate was 11.11 (9 of 81 cycles) in the CCHH group and 10.75 (10 of 93 cycles) in the HHCC group. The difference was not statistically significant. The cycle fecundity rate was 14.44% (13 of 90 cycles) for cycles with CC and 7.14% (6 of 84) with hMG. The difference was not statistically significant. CONCLUSION(S): These data suggest that CC is an effective alternative to hMG in the population examined.

Abortion, Spontaneous↗

PubMed2000

Gonadotropin and body mass index: high FSH levels in lean, normally cycling women.

OBJECTIVE: To characterize the relationships between body mass index (BMI) and LH or FSH levels over the cycle in normally cycling women. METHODS: We compared baseline characteristics, cycle characteristics, follicle sizes, and daily hormone levels among women with low (n = 22), normal (n = 63), or high (n = 22) BMIs over 326 cycles. RESULTS: There were no significant differences in age or other lifestyle characteristics between groups. High BMI was significantly associated with younger age at menarche and less sleeping time. No differences were observed between high- and low-BMI groups in cycle length or diameter of the dominant follicle. Luteinizing hormone levels were significantly higher only in the beginning of the cycle in women with low BMIs than in those with high BMIs. Follicle-stimulating hormone levels were also significantly higher but were high during all three phases of the cycle (early follicular, periovulatory, and luteal phases). Mean levels were approximately 1. 9, 1.8, and 1.2 times higher, respectively, in the low-BMI group than the high-BMI group. CONCLUSION: Luteinizing hormone levels and BMI were inversely associated in normally cycling women during the early follicular phase. Follicule-stimulating hormone levels and BMI were inversely associated during the whole cycle, independent of age.

Adolescent↗

PubMed2000

Sensitivity and specificity of ultrasound indices of ovulation in spontaneous cycles.

OBJECTIVE: Evaluation of sensitivity and specificity of 4 ultrasound indices of ovulation. STUDY DESIGN: Multicenter collaborative study of 794 abdominal and transvaginal ultrasound scanning of ovaries performed during 271 cycles in 107 normally fertile women. Comparison of sensitivities and specificities of indices using McNemar test. RESULTS: The sensitivity and specificity of the indices were 84 and 89.2, respectively, for disappearance or sudden decrease in follicle size; 38.4 and 79.7 for appearance of ultrasonic echoes in the follicle; 61.6 and 87.1 for irregularity of follicular walls; 71.0 and 88.2 for appearance of free fluid in the cul-de-sac of Douglas. CONCLUSION: Ultrasonic echoes had a significantly lower sensitivity (P<0.001) and specificity (P<0.01) than other indices.

Adult↗

PubMed2000

Unjustified variations in patient management for acute myocardial infarction in the Rhône-Alpes region of France. PRIMA Group.

OBJECTIVES: To examine determinants of use of cardiac procedures after acute myocardial infarction and identify variation factors. METHODS: Observational prospective cohort study of 2,519 patients in 48 centers with a two-level logistic-regression analysis. RESULTS: Elderly patients were less likely to undergo pre- and inhospital thrombolysis (odds ratios, 0.71 and 0.64; 95% CI, 0.62-0.81 and 0.58-0.69, respectively). The elderly, females, and patients with heart failure on admission were less likely to undergo noninvasive tests (0.74, 0.62, and 0.51; 95% CI, 0.67-0.81, 0.46-0.83, and 0.38-0.68, respectively) and coronary angiography (0.38, 0.53, and 0.67; 95% CI, 0.34-0.42, 0.38-0.74, and 0.52-0.86, respectively) but not revascularization. Hospital factors were more difficult to interpret. CONCLUSIONS: Elderly, women, and heart failure patients underwent fewer cardiac procedures than lower-risk patients. Physicians should change their attitude toward these groups and use advanced procedures, bearing in mind the patients' needs rather than good procedural outcomes.

Age Factors↗

PubMed2000

Low- versus high-osmolality contrast media.

PURPOSE: To evaluate the effects of contrast media pharmokinetic differences on aortic enhancement at abdominal CT angiography and to determine whether these effects are of clinical relevance. MATERIAL AND METHODS: Two hundred and twelve patients referred for abdominal CT angiography were included in the study. All abdominal CT angiograms were performed with the same parameters (collimation 3 mm, pitch ratio 1.7, scan delay 30 s) after i.v. injection of 120 ml of contrast medium at 3 ml/s. After randomization, patients received either iobitridol 300 (low-osmolar, 300 mg I/ml), iobitridol 350 (low-osmolar, 350 mg I/ml) or ioxithalamate 350 (high-osmolar, 350 mg I/ml). The time attenuation curves obtained with the three contrast media were compared. RESULTS: The time attenuation curve obtained with ioxithalamate 350 was not parallel to those obtained with iobitridol 300 and iobitridol 350. Mean peak enhancements obtained with iobitridol 350 and ioxithalamate 350 were not significantly different but iobitridol 350 provided higher mean peak enhancement than iobitridol 300. Mean delays of the peak enhancements were the same with the three contrast media. After peak enhancement, the decrease of aortic opacification under a selected threshold of 200 HU was significantly slower with iobitridol 350 than with iobitridol 300 and ioxithalamate 350, whereas iobitridol 300 and ioxithalamate 350 showed no significant differences. CONCLUSION: For a given iodine concentration, low-osmolality contrast media provide longer aortic opacification and may be recommended for CT angiography when long acquisition times are needed.

Adult↗

PubMed2000

Side of ovulation and cycle characteristics in normally fertile women.

This study was undertaken to establish whether ovulation in humans alternates consistently from right to left ovary in successive cycles and whether the site of ovulation affects the next cycle length or the hormonal profiles. A total of 199 cycles in 80 normally fertile women were studied. The volunteers were monitored with ultrasonography to determine the day and side of ovulation and to calculate follicular and luteal phase lengths. Urinary hormone concentrations were also assayed. Right-sided ovulations occurred in 104 of the 199 cycles (52.3%; not significantly different from 50%). Alternate ovulations occurred in 61 of the 119 pairs of succeeding cycles (51.3%, not significant). The follicular phase length in contralateral ovulation (14.59 +/- 0.33 days; mean +/- SEM) did not differ significantly from that of ipsilateral ovulation (14.59 +/- 0. 37 days). There were also no significant differences in urinary concentrations of oestrone-3-glucuronide, pregnanediol-3alpha glucuronide, follicle stimulating hormone, and luteinizing hormone between ipsilateral and contralateral ovulation in either early follicular, peri-ovulatory or luteal phase of the cycle. It is concluded that in normally fertile women, the cycle length and the hormonal profile are independent of the, most probably random, site of ovulation.

Adolescent↗

PubMed2000

Multivariate parametric random effect regression models for fecundability studies.

Delay until conception is generally described by a mixture of geometric distributions. Weinberg and Gladen (1986, Biometrics 42, 547-560) proposed a regression generalization of the beta-geometric mixture model where covariates effects were expressed in terms of contrasts of marginal hazards. Scheike and Jensen (1997, Biometrics 53, 318-329) developed a frailty model for discrete event times data based on discrete-time analogues of Hougaard's results (1984, Biometrika 71, 75-83). This paper is on a generalization to a three-parameter family distribution and an extension to multivariate cases. The model allows the introduction of explanatory variables, including time-dependent variables at the subject-specific level, together with a choice from a flexible family of random effect distributions. This makes it possible, in the context of medically assisted conception, to include data sources with multiple pregnancies (or attempts at pregnancy) per couple.

Biometry↗