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Biomedical subjects

A Ciampi

Publications and source records attributed to A Ciampi.

At least 37 records · Page 2Linked to original sources
PubMed1993

Role of the complete blood count in detecting occult focal bacterial infection in the young febrile child.

Previous studies of the value of the complete blood count (CBC) in distinguishing viral from bacterial infection in young febrile children have failed to exclude children with clinically evident bacterial infection and thus have inflated the positive predictive value of the test for occult focal infection. We prospectively studied 2492 children 3-24 months of age who presented to a children's hospital emergency department between March 1989 and August 1990 with fever (> or = 38.0 degrees C) of acute (< or = 4 days) onset but no evident bacterial focus of infection, 433 (17.4%) of whom received a CBC. We also carried out an 8-year retrospective analysis to estimate prior, or pre-test, probabilities (prevalences) and examine CBC results for rare occult bacterial infections (meningitis, osteomyelitis, and septic arthritis). Estimated prior probabilities for the four most common categories of infection that can be diagnosed at the initial visit were: non-pneumonitic viral infection, 88.6% in boys and 86.0% in girls; pneumonia, 8.5% in both sexes; urinary tract infection (UTI), 3.0% in boys and 5.5% in girls; and bacterial meningitis, 0.0066% in both sexes. The likelihood (sensitivity) of a total white blood cell (WBC) count > or = 15,000/mm3 was 25.5, 64.5, 62.5, and 50.0% for viral infection, pneumonia, UTI, and meningitis, respectively. Among children with a high total white blood cell count, neither a total polymorphonuclear count > or = 10,000/mm3 nor a band count > or = 500/mm3 was associated with significantly elevated likelihoods for occult pneumonia or UTI, a finding confirmed by multiple logistic regression analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1993

The longterm prognosis of lupus nephritis: the impact of disease activity.

An inception cohort of 87 patients with lupus nephritis was evaluated using a classification tree regression technique. Four relevant outcomes were studied: (1) renal insufficiency (serum creatinine > 5.0 mg/dl); (2) renal failure; (3) death due to renal involvement; and (4) any death due to systemic lupus erythematosus. All 4 outcomes could be predicted by one or more renal severity measures (serum creatinine, 24-h urinary protein excretion, nephrotic syndrome, or duration of prior renal disease), and among those with nonsevere renal disease, with a single disease activity measure (the National Institutes of Health or le Riche index). In general 3 prognostic groups (high, intermediate and low risk) could be identified for each outcome. Our results demonstrate the value of regression tree techniques in studies of prognosis and are compatible with a hypothesis of the interaction of disease activity with organ damage in lupus nephritis.

Adult↗
PubMed1992

NHPPREG: a computer program for the analysis of nonhomogeneous Poisson process data with covariates.

A program written in C is described which finds maximum likelihood estimates of regression coefficients and other relevant parameters for a point process with covariates. The data are assumed to come from a Poisson point process and may be modelled, at the user's choice, either totally parametrically or semi-parametrically. Furthermore, extra Poisson variation may be introduced, in both the parametric and semi-parametric approach, by the device of random effects. The work closely follows the theory developed by Lawless (1987).

Humans↗
PubMed1991

RECPAM: a computer program for recursive partition and amalgamation for survival data and other situations frequently occurring in biostatistics. III. Classification according to a multivariate construct. Application to data on Haemophilus influenzae type b meningitis.

The methodology of RECursive Partition and AMalgamation (RECPAM) previously presented in Parts I and II (A. Ciampi et al., Computer. Methods Progr. Biomed. 26 (1988) 239-256 and 30 (1989) 283-296) pursues its development with an application to predict long-term effects of a disease given a set of clinical information measured at the time of illness. This paper illustrates how RECPAM deals with a situation typical in Medical Informatics applied to data on Haemophilus influenzae type b meningitis.

Adolescent↗
PubMed1991

The risk of developing disease for siblings of patients with insulin dependent diabetes mellitus.

We analyzed the risk of developing insulin-dependent diabetes mellitus (IDDM) in 411 siblings of patients with IDDM. We found that siblings who had a positive test for antibodies against islet cells (ICA) at the time of diagnosis of the index case had a higher risk of developing IDDM than did those who had negative tests. However, of the ten siblings who developed IDDM, only four were positive at the initial testing. The period of time elapsing from a negative test at screening to a positive test at diagnosis varied but was less than one year in one child. Two of the ten siblings who developed IDDM had negative tests both at screening and at diagnosis. Amongst siblings who were negative at the initial screening, those in whom the index case was diagnosed at a young age had a higher risk of developing IDDM than did those in whom the index case was diagnosed at an older age. The age of the sibling at the time of screening, the sex of the sibling, and a positive family history (one which includes in addition to the index case one or more first-degree relatives with IDDM) did not confer increased risk. Our data suggest that screening for ICA will have to be done often and will have to be continued into adult life in order to identify the 70-80% of diabetics who will be positive at some time in the evolution of their disease.

Adolescent↗
PubMed1990

The sequelae of Haemophilus influenzae meningitis in school-age children.

BACKGROUND: Previous data on the consequences of Haemophilus influenzae type b meningitis for school-age children have been inconsistent, and much of the information on risk factors has been inconclusive. The present study was designed to evaluate the sequelae of this disease with a protocol for the comprehensive assessment of neuropsychological function. METHODS: Ninety-seven school-age children (mean age, 9.6 years), each of whom had a school-age sibling, were recruited from a survey of the medical records of 519 children treated for H. influenzae type b meningitis between 1972 and 1984 (at a mean age of 17 months) at the children's hospitals of Toronto, Ottawa, and Montreal. Of the 97 children, 41 had had an acute neurologic complication. Sequelae were assessed by comparing the index children with their nearest siblings on the basis of standardized measures of cognitive, academic, and behavioral status. RESULTS: Only 14 children (14 percent) had persisting neurologic sequelae: sensorineural hearing loss in 11 (unilateral in 6 and bilateral in 5), seizure disorder in 2, and hemiplegia and mental retardation in 1. Although the total sample of index children scored slightly below the siblings in reading ability, the 56 children without acute-phase neurologic complications (58 percent) were indistinguishable from their siblings on all measures. The differences between the groups were small even for the 41 pairs in which the index child had had an acute neurologic complication (mean full-scale IQ, 102 for the index children vs. 109 for the siblings). Sequelae were also associated with lower socioeconomic status and a lower ratio of glucose in cerebrospinal fluid to that in blood at the time of the meningitis. Behavioral problems were more prominent in index boys than index girls and in those who were older at the time of testing, but sex and age were not related to cognitive or academic sequelae. CONCLUSIONS: We find a favorable prognosis for the majority of children who are treated for meningitis caused by H. influenzae type b.

Adolescent↗
PubMed1990

RECPAM analysis of prognostic factors in patients with stage III breast cancer.

A retrospective chart review was conducted of women with stage III breast cancer seen at the Princess Margaret Hospital between January 1977 and December 1980. Three hundred and sixty-nine patients were available for analysis. These cases were evaluated to determine the prognostic factors of patients presenting with this stage of the disease using a recursive partitioning technique, RECPAM, and a Cox regression model. A non-mathematical description of RECPAM is presented and the advantages of RECPAM over Cox analysis are discussed. The results identify primary tumour size, axillary node involvement, internal mammary node involvement, and estrogen receptor status as the most important prognostic variables. RECPAM identified 3 prognostic groups and simultaneously provided rules based on the prognostic variables to assign patients to poor, intermediate, or good prognosis categories. Patients with estrogen receptor negative tumours, or those with axillary node involvement, primary tumours greater than 5 cm, and serum alkaline phosphatase greater than 60 IU/L, or those with internal mammary node involvement, no skin changes, and serum alkaline phosphatase greater than 60 IU/L, define a group with a poor prognosis. Patients with estrogen receptor positive tumours, no axillary node involvements, and primary tumours greater than 5 cm, or estrogen receptor positive tumours, axillary node involvement, primary tumours greater than 5 cm, but serum alkaline phosphatase less than or equal to 60 U/L, have an intermediate prognosis. The good prognosis group consists of those patients with estrogen receptor positive tumours who have either skin changes or primary tumours less than or equal to 5 cm. The effect of loco-regional and systemic therapy was assessed and there was no association between treatment assignment and prognostic group. On the basis of this RECPAM analysis, we have defined important prognostic variables to be used in the design of clinical trials, and three major patient subgroups which can be used in routine oncologic practice as a guide to patient management.

Biomarkers, Tumor↗
PubMed1990

Cluster analysis of an insulin-dependent diabetic cohort towards the definition of clinical subtypes.

Clinical and biochemical data on 111 consecutive insulin-dependent diabetic children enrolled in a longitudinal prospective study were analyzed to determine if more than one clinical expression of Type I diabetes exists. Use of multivariate statistical methods, including Correspondence Analysis, kappa-means clustering and RECPAM (RECursive Partition and AMalgamation), show that there are two well differentiated clinical expressions of IDDM each characterized by a cluster. One is characterized by later age, less severe onset, longer symptom duration, less beta-cell disappearance after 12 months, more females; the other by earlier age, more sudden and severe onset, DR 3/4, earlier disappearance of beta-cell function and more males. RECPAM analysis provides further insight into the structure of the two clusters. An other RECPAM tree identifies low, medium and high risk groups of disappearance of beta-cell function at 12 months after diagnosis.

Adolescent↗
PubMed1990

Parents' vs physicians' utilities (values) for clinical outcomes in potentially bacteremic children.

Our previous analyses of decision strategies in children 3-24 months with acute-onset fever greater than or equal to 39 degrees C and no evident bacterial focus of infection indicated that the risks of routine blood cultures (the unnecessary hospitalization and treatment of children who clear their bacteremia spontaneously) outweigh its benefits (the prevention of a few cases with major infectious sequelae). Because those analyses were based on parents' values for beneficial and adverse clinical outcomes, we wished to examine whether those values differed in physicians and, if so, whether the differences were sufficient to change the results of the decision analysis. Using a pre-tested linear analog utility (value) scale, we evaluated eight potential clinical outcomes in potentially bacteremic children by surveying 121 parents of healthy 3-24-month-old children attending a private pediatric group practice and 57 attending physicians of a tertiary-care children's hospital emergency room. Utilities were based on a 0-1 normalization, where 0 is the utility of the worst outcome (meningitis or other major bacterial infection, plus venipuncture), and 1 the utility of the best outcome (complete recovery without venipuncture or hospitalization), and were analyzed using a recently developed statistical model of utility. The majority of parents and physicians combined the imputed components of the outcomes (disease, pain of venipuncture, and stress of hospitalization) in a nonlinear fashion. Parents assigned substantially lower utility (i.e. greater disutility) to venipuncture, minor infection, and hospitalization than did physicians, and these utilities were even lower in parents with other children at home.(ABSTRACT TRUNCATED AT 250 WORDS)

Attitude of Health Personnel↗
PubMed1990

X-linked hypophosphatemia: the mutant gene is expressed in teeth as well as in kidney.

Mutation at a locus (HPDR) on the X chromosome (McKusick 30780 [HPDR1]; 30781 [HPDR2]) causes impaired renal phosphate transport, hypophosphatemia, and an associated impairment in the process of mineralization in bone and teeth (X-linked hypophosphatemia [XLH]). We measured the dental pulp profile area (PRATIO [= pulp area/tooth area]) and serum phosphorus (Pi) values in uniformly treated XLH patients (six males, 81 teeth, 1,457 Pi values; 11 females, 129 teeth, 1,439 Pi values). Serum Pi values, reflecting the metabolic environment of tooth development, were obtained by repeated measurement between 1 mo and 26 years of age during treatment. PRATIO values calculated from standardized Rinn radiographs were used as outcome measurements of tooth development in XLH patients and in age-matched controls (12 males, 100 teeth; 27 females, 275 teeth). Age-dependent serum Pi values were not different in the treated XLH males and females. In teeth forming primary dentin there was no gene dosage effect on PRATIO values apparent in subjects below 15 years of age. However, in teeth forming secondary dentin a gene dosage was found in the subjects aged 15 to 25 years: XLH male teeth (n = 65) mean +/- SD = 0.163 +/- 0.046; XLH female teeth (n = 75) mean +/- SD = 0.137 +/- 0.039; control teeth (n = 209) mean +/- SD = 0.116 +/- 0.023; (higher PRATIO values mean less development or mineralization of secondary dentin); differences in these PRATIO values (males vs. female and XLH vs. control) were significant by mixed-model analysis of variance.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

GENCOV: a Fortran program that generates randomly censored survival data with covariates.

We present a Fortran program for simulating censored survival data with covariates under the assumption of random censoring. The program generates times distributed according to the uniform distribution, the generalized Gamma distribution, the log-normal distribution and Pettitt's generalized logistic distribution with Box-Cox transformation of the time variable. Covariates can be introduced in the definition of the survival time, resulting in the generalized log-gamma, log-normal and Pettitt's regression models. Thereby the program provides the means for generating censored survival data according to parametric versions of three common regression models for censored survival data: the Accelerated Failure Time, the Proportional Hazards and the Proportional Odds models.

Computer Simulation↗
PubMed1989

RECPAM: a computer program for recursive partition amalgamation for censored survival data and other situations frequently occurring in biostatistics. II. Applications to data on small cell carcinoma of the lung (SCCL).

The RECPAM methodology previously presented in part I (A. Ciampi et al., Comput. Methods Programs Biomed. 26 (1988) 239-256) is applied to the analysis of survival data on small cell carcinoma of the lung (SCCL). It is shown how RECPAM can help answer the following questions which occur frequently in the analysis of clinical data: Is it possible to find a classification of patients with a certain disease into distinct prognostic groups? Given a covariate of special interest, does it have an independent prognostic significance even after confounding is taken into account? Does the prognostic significance of a covariate of special interest vary across patient subgroups? For the SCCL data, a prognostic classification is obtained and the tumor marker LDH is treated as a variable of special interest. Many features of RECPAM are illustrated, including, among others, Forward and Backward (Pruning) Stopping Rules, treatment of missing data, and use of several dissimilarity measures.

Biomarkers, Tumor↗
PubMed1988

Regression and recursive partition strategies in the analysis of medical survival data.

Regression and clustering methods have both been used to explore the effects of explanatory variables on survival times for patients with cancer or other chronic diseases. This paper discusses effective and computationally feasible approaches for this task in situations where there are fairly large and complex data sets; the techniques stressed are all-subsets regression and a kind of recursive partition clustering. We compare the two approaches in a rather general way, in part by examining some survival data for patients with ovarian carcinoma, and conclude that both have strong points to recommend them.

Female↗
PubMed1987

Ovarian cancer: ten-year experience in a community hospital.

We reviewed 187 patients with epithelial ovarian cancer treated, from 1975 to 1985, at the Division of Radiotherapy and Medical Oncology, Pordenone General Hospital, Italy. It seemed of interest to report an experience carried out in a community hospital in a consecutive unselected series of patients affected by ovarian cancer. Survival time was evaluated from the day of the primary surgical approach to the end of the study (March 1985). The aim of the study was to confirm in our patient population the importance of some already recognised prognostic factors that influence survival (age, stage, histology, grade, type of surgery and residuum). We also analyzed the effect of the treatment variables chemotherapy and radiotherapy on survival. The general pattern of prognostic factors appears to be in agreement with reports in the literature. In our experience, residual disease and stage were the main important prognostic factors; grade and histology had a secondary relevance, and age did not seem to be a prognostic factor in our population. New chemotherapy regimens and/or radiotherapy did not appear to improve survival. In fact, comparison of the results obtained from 1975-1979 and from 1980-1985 (when more aggressive surgery and cisplatin-containing regimens were employed) showed no statistically significant difference in survival rate. Our data suggest that patients at an early stage can receive a satisfactory quality of care in a general hospital with oncology facilities, provided the surgeon and the pathologist are experienced in ovarian cancer. Patients at stage III but completely surgically resected can also be adequately treated. Patients with advanced disease, considering the lack of established efficacious treatments, should be referred to specialized centers, where new drugs or experimental strategies can be tested.

Adult↗
PubMed1986

Malignant gliomas of the brain. A retrospective study.

A retrospective study of 72 consecutive and nonrandomized patients with malignant glial tumors is presented. The influence of age, sex, location of tumor, initial presenting symptoms, symptomatic preoperative interval, reoperation, extent of tumor removal, histological subtype of tumor, lymphocyte infiltration, and different treatments upon survival time has been evaluated and statistically analyzed. Age was inversely associated with survival with a strong statistical significance (p = 0.0001). Headache was the most common (67%) initial symptom; aphasia and seizure were both present in 45.3% of patients. Initial presenting symptoms had no effect upon survival. Parietal lobe and lymphocyte infiltration had marginally negative effects upon survival (p = 0.097 and p = 0.10 respectively). The amount of tumor removal was marginally associated with an improved survival (p = 0.07). Radiation therapy was strongly associated with an improved survival time (p = 0.0007). The addition of chemotherapy did not affect the survival (perhaps reflecting the small number of patients and inadequate chemotherapy). There was an obvious beneficial effect of reoperation upon survival time, if the patient lived and underwent reoperation later than 16 months after the initial operation (slow-growing tumor). Although median and mean survival times (10 and 20.34 months respectively, SD 7.45 months) were similar to most series reported, our rates of survival (20%, 12.5%, and 7.5% at 2, 3, and 5 years, respectively) were notably higher.

Adult↗
PubMed1986

Multi-type Galton-Watson process as a model for proliferating human tumour cell populations derived from stem cells: estimation of stem cell self-renewal probabilities in human ovarian carcinomas.

A mathematical model for proliferation of tumour cell populations is developed. The cell population is assumed to be organized in a hierarchy of decreasing proliferative potential and increasing degree of differentiation. Using some elements of the theory of Multi-type Galton-Watson processes, a method is proposed for the estimation of Psr, the probability of self-renewal of tumour stem cells, from the experimental distribution of clonal unit sizes obtained in cell culture studies. Six data sets from patients with advanced adenocarcinoma of the ovary are used to demonstrate the method. Reasonable estimates are obtained, and the theoretical colony size distributions predicted by the model appear to be in good qualitative agreement with the experimental ones, and lend support to a stem cell model of tumour growth. The possible significance of Psr as a prognostic factor is briefly discussed.

Cell Division↗
PubMed1985

GFREG: a computer program for maximum likelihood regression using the Generalized F distribution.

A FORTRAN program is described for maximum likelihood estimation within the Generalized F family of distributions. It can be used to estimate regression parameters in a log-linear model for censored survival times with covariates, for which the error distribution may have a great variety of shapes, including most distributions of current use in biostatistics. The optimization is performed by an algorithm based on the generalized reduced gradient method. A stepwise variable search algorithm for covariate selection is included in the program. Output features include: model selection criteria, standard errors of parameter estimates, quantile and survival rates with their standard errors, residuals and several plots. An example based on data from Princess Margaret Hospital, Toronto, is discussed to illustrate the program's capabilities.

Biometry↗