Gender difference in index and secondary patients with and without household contact

Abstract

To investigate gender difference in index and secondary patients with or without household contact. The subjects of this retrospective study were 3,174 pulmonary TB patients registered in Aichi prefecture between 1989 and 2003. All recorded files were reviewed to identify epidemiologically-related TB patient clusters. In case of epidemiologically-related patients registered within less than 10 years interval, the first registered patients was defined as the index case of the cluster. The other patients in the cluster were defined as secondary cases. Therefore, all pulmonary TB patients were classified to index, secondary, or unclustered cases. An index patient with sputum smear positive was defined as the source of transmission in the cluster. The male/female ratio was calculated separately in the sources and secondary patients with or without household contact. A total of 100 source patients were identified. Of these, 77 were male and 23 were female, and the male/female ratio was 3.3. The secondary patients were 153, of whom 77 were male and 76 were female, and the male/female ratio was 1.0. The difference of the male/female ratio was statistically significant (p<0.001). The male/female ratio in the source patients was 2.5 for 78 clusters with household contact and 21.0 for 22 clusters without household (p<0.05), while the ratio in the secondary patients were 0.8 and 2.2 respectively (p<0.01). Of the 111 secondary patients with household contact, the relations to the source patients were wife-husband in 32, parent-child in 55, brother or sister in 12, grandparent-grandchild in 8, and the others in 4. In the 32 wife-husband transmission, most secondary patients were female (male/female = 9/23) while in other 67 transmissions with household contact, male and female secondary cases were almost same (male/female= 39/40). The male/female ratios in these two settings were significantly different (0.4 vs 1.0, p<0.05). Of the 42 secondary patients without household contact, transmission were occurred in working places in 24, schools in 11, religion circles in 4, hospital in one, and others in 2. The male/female ratio of secondary cases was 7.0 for transmission at working places, and 0.8 for transmission at the other places (p<0.01). These findings suggest that the male/female ratio of secondary patients with household contact is significantly lower than that of those without household contact.