In this prospective study of IPT adherence and associated barriers in Indonesian children, only 26% of children collected their medication prescription four or more times. Indeed, 51% of all children did not return to the clinic after the first month of medication prescription. Such poor adherence is not unique. Research in TB endemic settings in South Africa found adherence rates for children < 5 years prescribed six months IPT to be between 15-28% [10, 11]. In Australia IPT adherence rates among six-year-old children were between 54-74%  and in Brazil only 53% of all household contacts completed IPT with 29% being immediately lost to follow-up .
While limited by the size of the main study cohort, quantitative analysis did indicate possible risk factors for poor adherence to IPT. These were predominately related to financial barriers for medication collection including cost of medication and transport, and low socio-economic status. Transport cost as a barrier was also frequently mentioned in the qualitative interviews. Financial barriers to IPT adherence have been found elsewhere. In Brazil TB household contacts prescribed IPT, who took two buses to reach the study clinic were 1.8 (95% CI 1.01-3.3) times as likely to be non-adherent compared to those who took only one bus. Authors attributed this to an increase in transport costs . Reduction of cost barriers through provision of IPT services at peripheral health centres was a dominant proposed solution in qualitative interviews.
Quantitative analysis suggested that side effects and other treatment problems might be associated with poor adherence. The importance of side effects was also a theme that emerged from the qualitative interviews. The negative effect of side effects has been sited elsewhere. In Tanzania 14% of HIV positive patients initiated on IPT did not complete therapy due to minor side effects,  in Australia 23/32 patients who experienced minor side effects stopped therapy  and in Thailand 10/72 HIV positive patients who missed more than one month of IPT did so because of the perceived side effects of INH .
We found older age to facilitate IPT adherence. This has been reported elsewhere [12, 15]. A South African study found older children were more likely to complete treatment. Authors postulated that difficulty in medication consumption explained this finding. Our study's qualitative findings support this; caregivers frequently expressed that difficulties in medication administration was a significant barrier. Ease of medication administration is especially important where drug regimens are lengthy in duration and for prevention only.
From qualitative interviews IPT knowledge and health beliefs were found to be important. Caregivers of children with good adherence frequently mentioned a desire for health while caregivers of children with poor adherence often expressed a belief that IPT is unnecessary for healthy children. Similarly, in Australia, from interviews with 67 families of children prescribed IPT, only 65% believed their child required therapy  while in South Africa reduced risk perception was commonly displayed by parents of non-adherent children .
This study has several limitations. The relatively small size limits multivariate analysis and strong inferences are restricted. However, the addition of a qualitative component strengthened conclusions supporting key quantitative findings. Adherence levels could only be measured by whether monthly prescriptions were collected and it cannot be determined whether the medication was actually bought and how much was administered to the child. However it seems reasonable to assume that most caregivers who made the effort to collect their prescription would also purchase and administer the medication, at least after the first month. It is possible that INH was acquired by caregivers at a peripheral health care centre resulting in misclassification and an underestimation of adherence rates. However for this to happen caregivers would have to seek further screening at the peripheral health care centre which seems unlikely. Further, on-going research at peripheral health care centres in this setting shows IPT is very rarely prescribed as a treatment option. Finally, this study was conducted in a single setting, limiting generalizability. Nevertheless the study site is a primary tuberculosis and lung disease referral clinic and the children are likely representative of child case contacts in the city. Further, all eligible child case contacts from consecutively diagnosed sputum smear positive adult TB cases were prospectively and actively screened, reducing selection bias that may exist where only passively screened children initiated on IPT are investigated .