COCKROACH ALLERGY IN KENTUCKY - A COMPARISON OF INNER-CITY, SUBURBAN,AND RURAL SMALL-TOWN POPULATIONS

The cockroach has been reported as a major allergen in inner city asth matic patients. The retrospective chart review of 799 patients tested over a 10-year period (1981-1991) derived from a private allergy pract ice and a university allergy clinic is reported. Patients from both gr oups were divided geographically by home zip codes into inner city, su burban, or rural small town populations. Criteria for positive skin te sts were wheal greater than 5 mm for prick and greater than 10 mm for intradermal tests with flare. Overall, 36.9% (295/799) of all patients surveyed were positive by either prick or intradermal skin testing. C ockroach reactivity was observed in 38.6% (95/246) of the private pati ents tested with 36.2% (200/553) of the university patients showing po sitive results. The inner city populations in both groups of patients were similar with 43.7% and 40.3% of the private and university patien ts, respectively, testing positive, with an overall positivity of 41% for all inner city patients. Inner city and rural small town populatio ns for both study groups demonstrated almost identical reactivity with 41% and 43% overall positivity, respectively. Of the suburban group, 37.5% of the private patients and 28.8% of the university patients had reactive skin tests results with an overall rate of positivity of 30. 1%. This rate (30.1%) is significantly less than the rate for either i nner city (41.0%, P <.05) or rural small town (43.6%, P <.01) populati ons. Cockroach was not a common allergen in children under 3 years of age (skin tests positive in 15%); however, all cockroach allergic pati ents under 3 years of age had a diagnosis of bronchial asthma or react ive airway disease. The greatest prevalence of cockroach sensitivity ( 42%) was for children between 7 and 12 years of age. This rate was sig nificantly higher than for all other age groups (P <.05). Of all patie nts with a diagnosis of asthma 51.3% had a positive cockroach skin tes t as compared with 32.7% with allergic rhinitis only (P <.001). Cockro ach allergy is, therefore, a common sensitizer in both inner city and rural populations in Kentucky with allergic airway disease and is more commonly encountered in patients with asthma. Since cockroach may be asthmagenic, similar to dust mite via domestic infestation and respira ble house dust, we suggest that cockroach antigen needs to be included in the routine battery of inhalant skin tests for both adults and chi ldren of all ages and geographic locations.