Researchers investigated the association between Chlamydia pneumoniae infection and mortality in a cohort of 227 end-stage renal disease (ESRD) patients followed up for 40 months. Patients were divided into two groups according to the presence/absence of antibodies for C. pneumoniae: 138 patients were classified as seronegative and the remaining 89 patients as seropositive. Number of deaths/survivors in the study population according to the presence/absence of C. pneumoniae infection: C. pneumoniae infection Deaths Survivors Seropositive (n = 89) 38 51 Seronegative (n = 138) 40 98 What is the crude risk ratio (to 2 decimal places) for mortality among those positive for C. pneumoniae infections compared to those who were negative