Eventos adversos pós-vacina contra a difteria, coqueluche e tétano e fatores associados à sua gravidade / Adverse events following diphtheria, pertussis and tetanus vaccinations and factors associated with severity / Adverse events following diphtheria, pertussis and tetanus vaccinations and factors associated with severity

RESUMO

OBJETIVO: Avaliar os eventos adversos pós-vacina contra a difteria, coqueluche e tétano (EAPV-DPT) e os fatores associados à sua gravidade. MÉTODOS: Estudo transversal com componente descritivo e analítico, abrangendo os eventos adversos pós-vacina DPT notificados no Estado de São Paulo, de 1984 a 2001, entre crianças menores de sete anos de idade. A definição de caso foi a adotada pela vigilância de EAPV-DPT; os dados obtidos foram originados da vigilância passiva desses eventos. No cálculo das taxas, o numerador foram os EAPV e o denominador o número de doses aplicadas. A associação entre a gravidade dos EAPV-DPT e as exposições de interesse foi investigada pelas estimativas não ajustadas e ajustadas da odds ratio, com os respectivos intervalos de 95 por cento de confiança, usando regressão logística não condicional. RESULTADOS: Identificaram-se 10.059 EAPV-DPT relativos a 6.266 crianças, apresentando um ou mais EAPV, 29,5 por cento foram internadas e em 68,2 por cento houve contra-indicação das doses subseqüentes de DPT. Cerca de 75 por cento dos eventos ocorreram nas primeiras seis horas após a aplicação da vacina. Os eventos mais freqüentes foram febre<39,5°C, reação local, evento hipotônico hiporresponsivo e convulsão. Mostraram-se independentemente associadas à gravidade intervalo inferior a uma hora entre a aplicação da vacina e o evento (OR=2,1), primeira dose aplicada (OR=5,8), antecedentes neurológicos pessoais (OR=2,2) e familiares (OR=5,3). CONCLUSÕES: A vigilância passiva de EAPV mostrou-se útil no monitoramento da segurança da vacina DPT, descrevendo as características e a magnitude desses eventos, assim como permitiu identificar possíveis fatores associados às formas graves.

ABSTRACT

OBJECTIVE: To analyze adverse events following vaccinations against diphtheria, pertussis and tetanus (AEFV-DPT) and to investigate factors associated with event severity. METHODS: A cross-sectional study was carried out with a descriptive and analytical component covering AEFV-DPT that were notified in the State of São Paulo, Brazil, between 1984 and 2001, among children less than seven years old. Cases were defined as used in AEFV-DPT surveillance; the data source was AEFV-DPT passive surveillance. In calculating the rates, the numerator was the number of AEFV-DPT and as denominator was the number of doses applied. The association between severity of AEFV-DPT and the exposures of interest was investigated by means of non-adjusted and adjusted estimates of odds ratios, with their respective 95 percent confidence intervals, using non-conditional logistic regression. RESULTS: A total of 10,059 AEFV-DPT were identified, corresponding to 6,266 children who presented one or more AEFV-DPT, 29.5 percent were hospitalized and 68.2 percent presented contraindications for subsequent DPT doses. Around 75 percent of the events occurred during the first six hours after vaccination. The most frequent AEFV-DPT were fever < 39.5°C, local reactions, hypotonic-hyporesponsive episodes and convulsion. Time interval of less than one hour between vaccination and the event (OR = 2.1), first dose applied (OR=5.8) and previous personal (OR=2.2) and family (OR=5.3) neurological histories were independently associated with severe events. CONCLUSIONS: Passive surveillance of AEFV-DPT was shown to be useful for monitoring the safety of the DPT vaccine, through describing the characteristics and magnitude of these events, and also enabling identification of possible factors associated with severe forms.