These factors combine to render older estimates of coprolalia—biased towards clinical populations of the more severe cases—outdated. An international, multi-site database of 3,500 individuals with Tourette syndrome drawn from clinical samples found 14% of patients with Tourette's accompanied by comorbid conditions had coprolalia, while only 6% of those with uncomplicated ("pure") Tourette's had coprolalia. The same study found that the chance of having coprolalia increased linearly with the number of comorbid conditions: patients with four or five other conditions—in addition to tics—were four to six times more likely to have coprolalia than persons with only Tourette's.[18] One study of a general pediatric practice found an 8% rate of coprolalia in children with Tourette syndrome, while another study found 60% in a tertiary referral center (where typically more severe cases are referred).[19] A more recent Brazilian study of 44 patients with Tourette syndrome found a 14% rate of coprolalia;[20] a Costa Rican study of 85 subjects found 20% had coprolalia;[21] a Chilean study of 70 patients found an 8.5% rate of coprolalia;[22] older studies in Japan reported a 4% incidence of coprolalia;[23] and a still older clinical study in Brazil found 28% of 32 patients had coprolalia.[24] Considering the methodological issues affecting all of these reports, the consensus of the Tourette Syndrome Association is that the actual number is below 15 percent.