[en] AIM To determine the efficacy of exhaled carbon monoxide (CO) measurement plus smoking brief advice, in comparison to brief advice, to reduce smoking exposure and smoking behaviour in smoking kidney transplant recipients, in the precontemplation, contemplation or preparation stage of change, in terms of: a) Pattern of tobacco use (self-reported tobacco use) b) Smoking cessation rates c) Carbon monoxide (CO) levels in exhaled air measured by cooximetry d) Negative urine cotinine test e) Nicotine dependence (Fagestréim's test) f) Motivation to stop smoking (Prochaska and DiClemente's Stages of Change Model) g) Motivation to quit smoking (Richmond's test) MATERIAL AND METHODS Scope: Nephrology Department, Complejo Hospitalario Univesitario A Coruña (CHUAC). Study period: January 2012 - December 2015. Type of study: Randomized, controlled, open clinical trial with blind evaluation. Inclusion I exclusion criteria: Adults (>18 years), smoking kidney transplant recipients with a functioning graft, in the precontemplation, contemplation or preparation stage of change, who give their consent to participate. Intervention: Exhaled carbon monoxide (CO) measurement plus brief advice to quit smoking, compared with isolated brief advice. Sample size: Intervention group (n=56), control group (n=56) (a = 0.05, f3 = 0.20; minimally clínical relevant difference 13%). Measurements: Socio-demographic characteristics, cardiovascular risk factors, selfreported tobacco use, level of dependence (Fagerstrom's Test), motivation to quit smoking (Prochazka and Di Clemente's stage of change), motivation to stop smoking (Richmond's test), cotinine urine test and exhaled carbon monoxide (CO), measured by co-oximetry. Statistical analysis: Patients' response in both study arms was compared using a bivariate and multivariate logistic regression analysis. Clinical relevance was calculated by means of the relative risk (RR), relative risk reduction (RRR), absolute risk reduction (ARR) and the number needed to treat to reduce an event (NNT). RESUlTS At 12 months of follow-up, significant differences were found in exhaled CO measurements between the intervention and the control group (6.1 ± 6.8 vs. 10.2 ± 9.7 ppm; p=0.028). Carboxyhemoglobin (% COHb) levels resulted also significantly lower in the intervention group (1.2 ± 1.2 vs. 2.0 ± 2.4%; p=0.039). Furthermore, percentage of patients with a positive cotinine urine at the end of the study was lower in the intervention than in the control arm (53.4% vs. 74.2%). At different points in the follow-up, significant differences were also found between both groups of patients regarding their motivation to quit smoking, according with the Prochaska and OiClemente's stages of change. Therefore, at 12 months, there were more patients in the abandonment stage in the intervention than in the control group (46.6% vs. 32.3%). The same trend was observed at 6 months of follow-up. No significant differences between both groups were determined in terms of selfreported tobacco use (number of cigarettes/day), smoking rate, nicotine dependence (Fagerstrom's test) nor in the motivation to stop smoking (Richmond's test). However, the trend was that patients in the intervention arm showed lower self-reported tobacco use and lower nicotine dependence during all the follow-up. Agreement between self-reported tobacco use and urine cotinine test results was high, according to Kappa index results. However, low negative likelihood ratios indicate that a negative self-report does not rule out the smoking status. Conversely, a high positive likelihood ratio as that obtained at 6 months (40.41) indicates that a positive self-report almost confirm the exposure. In the multivariate analysis (adjusted OR), after taking into account the variables: age at baseline, self-reported tobacco use, nicotine dependence (Fagerstrom's test), motivation to quit smoking (Richmond's test), gender and treatment group; variables with an independent effect to predict a positive cotinine urlne test were: being assigned to the intervention group, motivation to quit smoking at baseline and baseline self-declared tobacco use. Being in the intervention group significantly reduces the risk of a positive cotinine urine test (OR=0.39; 95% CI: 0.17 to 0.89). The highest motivation to quit in turn reduces the risk of a positive result (OR=0.83; 95% CI: 0.68 to 0.99), whilst the self-declared tobacco consumption (cigarettes/day) increases the risk (OR 1.09; 95% CI: 1.02-1.16). Clinical relevance of the intervention has been measured with regard to a negative cotinine urine test during the follow-up. At 12 months, the intervention reduces by 28% the probability or a positive urine test, in comparison with the control group. Moreover, the NNT at 12 months shows that in 5 patients where we do an intervention, get one stop smoking. CONCLUSIONS The use of cooximetry, in smoking kidney transplant recipients, is a clinically relevant intervention to reduce tobacco exposure.

[gl] OBXETIVO Determinar a eficaza da medición de monóxido de carbono (CO) exhalado por cooximetría xunto co consello breve para deixar de fumar ós 12 meses en comparación cun consello breve IIlado en pacientes trasplantados renais fumadores, en fase de precontemplación, contemplación ou prepraración, en relación a: a) Consumo de tabaco autodeclarado b) Tasas de abandono do tabaco c) Niveis de monóxido de carbono (CO) en aire exhalado por cooximetría d) Test de cotinina en ouriños negativos e) Grao de dependencia a nicotina (test de Fagerstriim) f) Motivación ó cambio (Etapas Prochaska, DiClemente) g) Motivación para deixar de fumar (test de Richmond) MATERIAL E MFrODOS Ámbito: Servizo de Nefroloxía do Complexo Hospitalario Universitario A Coruña (CHUAC). Periodo do estudo: Xaneiro2012 - Decembro2015. Tipo de estudio: Ensaio clínico aleatorizado, controlado e aberto con avaliación cega. Criterios de inclusión/exclusión: Adultos (>18anos), trasplantados renais con inxerto funcionante, fumadores en etapa de precontemplación, contemplación ou preparación que dean o seu consentemento para participar. Intervención: Medición do monóxido de carbono (CO) exhalado xunto co consello breve para deixar de fumar en comparación cun consello breve illado. Tamaño da mostra: Grupo de intervención(n=56), grupo control(n=S6)(a=O.05; ~=O.20; diferencia a detectar 13%). Medicións: Características sociodemográficas, factores de risco cardiovascular, información autodeelarada do hábito tabáquico, nivel de dependencia á nicotina (Test de Fagerstrom), fase de abandono (Prochazka y Di Clemente), motivación para deixar de fumar (Test de Richmond), test de cotinina en ouriños e monóxido de carbono (Ca) exhalado por cooximetría. Análise estatístico: Comparo use a tasa de res posta dos pacientes nos dous brazos do estudo mediante un análise bivariado e multivariado de regresión loxística. Calculouse a relevanza el ínica mediante o cálculo do risco relativo (RR), reducción relativa del risco (RRR), reducción absoluta do risco (RAR) e número necesario de pacientes a tratar para reducir un evento (NNT). RESULTADOS Obxetiváronse diferenzas significativas ós 12 meses entre o grupo da intervención e o grupo control no monóxido de carbono (Ca) exhalado por cooximetría (ppm) (6.1±6.8 vs. 9.7±10.2 ppm; p=O.028). Así como na carboxihemoglobina exhalada por cooximetría (% COHb) (1.2±1.2 vs. 2.0±2.4 %; p=O.039). Os valores de cotinina en ouriños positivos foron tamén estadísticamente diferentes ó remate do estudo entre o grupo da intervención e o grupo control. No grupo da intervención a prevalenza de positivos foi do 53.4% e no grupo control do 74.2%. Tamén se obxetivaron diferenzas estadísticamente significativas entre o grupo da intervención e o grupo control en diferentes momentos do seguemento en relación á motivación ó cambio (estadios de Prochaska e DiClemente). Ós 12 meses, no grupo da intervención encóntranse máis pacientes no estado de abandono do tabaco que no grupo control (46.6% vs. 32.3%). A mesma tendencia obxetivase ós 6 meses. Non se obxetivan diferenzas significativas entre ambos grupos nas variables consumo de tabaco autodeelarado (n° cigarrillos/d ía), tasa de fumadores (%), dependencia á nicotina (Test Fagerstrom) e motivación para deixar de fumar (Test Richmond). Aínda que non se obxetivan diferenzas entre ambos grupos nos valores de consumo autodeelarado de tabaco (n° cigarrillos/d ía), este valor é discretamente superior no grupo control que no grupo intervención ó longo do seguemento e a mesma tendencia objetivase na dependenza á nicotina (Test Fagerstrom). Existe unha alta concordancia entre o consumo de tabaco autodeclarado e o test de cotinina en ouriños positivo durante o seguemento, medida polo índice Kappa. Os cocientes de probabilidade negativos con valores baixos mostran de calquera forma que unha negación da exposición ó tabaco por parte do paciente non a descarta. Polo contrario, un cociente de probabilidade positivo con valores tan altos como o obtido ós 6 meses (40.41) indica que unha afirmación positiva prácticamente confirma a exposición. No análise multivariado (OR axustado), tras tener en consideración as variables: idade ó inicio do ensaio, consumo autodeclarado de tabaco, dependencia á nicotina (Test Fagerstrtim), motivación para deixar de fumar (Test Richmond), xénero e grupo obxetívase que as variables que teñen un efecto independiente para predecir positividade son o grupo de asignación ó estudo, a motivación para deixar de fumar medida por el test Richmond basal mente e o consumo autodeclarado de tabaco (cigarrillos/día) basal. Estar no grupo da intervención reduce significativamente o risco de test de cotinina en ouriños positivo (OR 0.39; 95% le: 0.17-0.89). A maior motivación para deixar de fumar reduce a súa vez o risco de ser positivo (OR 0.83; 95% le: 0.68-0.99) e o consumo autodeclarado de tabaco (cigarrillos/día) incrementa o dito risco (OR 1.09; 95% le: 1.02-1.16), a máis cigarrillos de consumo basal maior risco dun resultado positivo A relevancia clínica da intervención realizada mediuse por medio da confirmación do test de cotinina en ouri ños ó longo do seguemento entre ambos grupos. Os 12 meses obxetivase que a intervención reduce un 28% a positividade do test de cotinina en ouriños en relación ó grupo control. Por outra parte, o valor do NNT ós 12 meses, mostra que cada 5 pacientes nos que realizamos una intervención, logramos que un deixe de fumar. CONCLUSIÓNS A utilización da cooximetría en pacientes trasplantados renais fumadores, é unha intervención cI ínicamente relevante para reducir a exposición ó tabaco.