Introduction to Epidemiology 6th Edition by Ray M Merrill

Exercise 5

From Table I-14, which three combinations of “chemicals associated with congenital malformation” were the highest? Which chemicals were linked to and associated with malformations according to the odds ratio? Explain the assessment and themeaning of Table 1

Table 1 Odds Ratios for Congenital Malformations for All Infants with Specific Malformation Codes† and Residential Proximity to Selected Toxic Waste Sites Containing Associated Chemical Groups: New York State, 1983–1984

Chemical and Associated Malformation (Reference)	OR‡§	CI‡§
Pesticides/oral clefts (13–15)	1.27	0.84–1.92
Pesticides/musculoskeletal system (16, 17)	1.20*	1.05–1.38
Metals/nervous system (18–20)	1.34*	1.07–1.67
Solvents/nervous system (21–23)	1.24*	1.01–1.54
Solvents/digestive system (24, 25)	0.91	0.73–1.13
Plastics/chromosomal anomalies (26–29)	1.46*	1.01–2.11

* p<0.05.

† Previously related to chemical exposures in the literature.

‡ Data from ICD-9, International Classification of Diseases, 9th revision; OR = odds ratio; CI = confidence interval.

§ Adjusted for maternal age, race, education, complications during pregnancy, parity, population density for county of residence, and gender of the child, by logistic regression.

Step 1 of 3

Odds Ratio (OR) measures the association with, and dependence of an outcome on the exposure to a test material. It is thus a means of quantification of the strength of presence and absence of a test substance on the perceived outcome. It is calculated as the likelihood of occurrence of one condition, when a variable has already been applied to the likelihood of occurrence of the condition when a variable has not been applied.

Confidence interval (CI) is the set of probable values within which the population parameter must lie, such that the parameter under study can have values lying in the range of all probable values (one of which is the true value), calculated for that parameter under a given set of conditions.