Incidence of malignant neoplasms in children attending Social Security Hospitals in Mexico City.

An increase in neoplasms in Mexican children has been reported. In 1991, the incidence in children from Mexico City (MC) was 70 (x 10(6) child/year), although this rate might be underestimated. The aim of the present study was to estimate the incidence of malignant neoplasms in children resident in MC attending Social Security (SS) hospitals. This study was a retrospective hospital survey. All records of childhood malignant neoplasms diagnosed between 1992 and 1993 in the two SS hospitals which attend childhood neoplasms in MC were reviewed. Histopathological diagnoses were reevaluated and incidence rates (x 10(6) child/ year) in terms of age, sex, and place of residence were estimated. A total of 667 cases were found for the period of study, of which 199 corresponded to residents of MC. The neoplasms with highest prevalence were leukemias (39.2%), lymphomas (17.6%), and central nervous system tumors (12.6%). A general incidence of 94.3 was found, which was highest in children under 5 years of age. Leukemias had an incidence of 36.4, lymphomas of 15.2, and central nervous system tumors of 12.0. Prevalence was higher in boys (male/female ratio of 1.6). As for the place of residence, the highest incidence corresponded to children living in the southern areas of MC. Eighty percent of the leukemias were acute lymphoblastic, while 54% of solid neoplasms were classified as stages III and IV. In conclusion, the incidence of malignant neoplasms in children resident in MC treated at SS hospitals is consistent with that found worldwide, and also with the Latin American pattern.

[The consistency and validity of a measurement in clinical pediatric research. Its definition, evaluation and interpretation]. / Consistencia y validez de una medición en la investigaciíon clínica pediátrica. Definición, evaluación y su interpretación.

In clinical pediatric research as in all research, one of the fundamental characteristics is the measurement of the studied features, either clinical, of laboratory or cabinet. A measurement must have two fundamental characteristics, for it to be considered as scientific: consistency and validity. The first one is centered on the variability of the measurement, which is due to the measuring instrument, to the subject or entity which is measured and to the individual or individuals who carry out the measuring, this is known as intra or interobserver variability, respectively. Validity is the fact of "actually" measuring what we want to measure. Both characteristics of measurement, are often mixed, between them and with other concepts, and this is the reason of not having a clear idea of what is the real meaning. This paper discusses the different terms that have been used for consistency and validity of a measurement. Also it points out how to assess consistency, from the validity, taking into account the measuring scale of the variables and the number of observers. Easy examples are used for the application of different formulas and for the interpretation of the results.