Background Isoniazid (INH) prophylaxis is strongly recommended for the patients who have latent tuberculosis (TB) and who are going to be under anti-TNF treatment. INH is prescribed for 9 months and patient adherence to INH affects the risk of active TB development.

Objectives In this study we aimed to assess the levels of patient adherence to INH prophylaxis.

Methods Patients, who are under biological treatment and who have a quantiferon (QFT) test result, were evaluated with a questionnaire between August 2015-August 2016. Questionnaire included the demographic and clinical characteristics. Besides, patients were asked whether they had been prescribed INH. Patients, who were given INH prophylaxis, were asked to answer those questions: i) Did you take INH daily and regularly for 9 months? ii) If not what was the reason? The reasons are classified into three categories: 1) The patient discontinued INH of his/her own volition before 9 months. 2) Continued INH for 9 months but did not take regularly due to forgetfulness. 3) Treatment stopped by physicisan due to an adverse effect (elevation of liver enzymes, neuropathy, etc.)

Results 1. 710 patients were recruited. INH was prescribed to 169 (23.8%) of 710. Demographic characteristics of INH-prescribed patients: 88 (52.1%) of 169 were female, mean age was 46.2 (SD:11.4), 82 (48.5%) of 169 at least graduated from a high school. Diagnosis were followed; RA 65 (38.4%), SpA 85 (50.3%), PsA 13 (7.7%), others 6 (3.6%). Totally 34 (20.1%) of 169 took INH irregularly. 19 (11.2%) of 169 patients discontinued INH of his/her own volition before 9 months. During follow-up 5 of 19 were prescribed INH again by the physician and they completed the 9-months duration. 9 (5.3%) of 169 patients did not take INH regularly due to forgetting. INH was stopped by a physician due to liver enzyme elevation in 6 (3.5%) of 169 patients. There was not a statistically difference in demographical and clinical characteristics between regular and irregular INH takers.

Conclusions There is an inadherence to INH treatment approximately in one of five patients. Only 3.5% of INH-recommended patients had a medical reason of inadherence. Among other patients, causes of inadherence were discontinuance of own volition and forgetfulness or perfunctoriness. Physicians should be aware that reminding of INH is one of the question in every outpatient clinic visits. Other reminding methods such as regular calling should be considered in those of high risk population. Further studies were needed for reminding process.

Disclosure of Interest None declared