The level of evidence for all these regimens is poor, and there is little to recommend one over the other. Regimens omitting rifampicin
The UK prevalence of rifampicin (RMP) resistance is 1.4%. It is rare for TB strains to be resistant to RMP without also being resistant to INH, which means that rifampicin-resistance usually means resistance to INH as well (that is, MDR-TB). However, RMP intolerance is not uncommon (hepatitis or thrombocytopaenia being the most common reasons for stopping rifampicin). Of the first-line drugs, rifampicin is also the most expensive, and in the poorest countries, regimens omitting rifampicin are therefore often used. Rifampicin is the most potent sterilising drug available for the treatment of tuberculosis and all treatment regimens that omit rifampicin are significantly longer than the standard regimen. The UK recommendation is 18HE or 12HEZ. The US recommendation is 9 to 12HEZ, with the option of adding a quinolone (for example, MXF). Regimens omitting pyrazinamide
PZA is a common cause of rash, hepatitis and of painful arthralgia in the HREZ regimen, and can be safely stopped in those patients who are intolerant to it. Isolated PZA resistance is uncommon in M. tuberculosis, but M. bovis is innately resistant to PZA. PZA is not crucial to the treatment of fully sensitive TB, and its main value is in shortening the total treatment duration from nine months to six. An alternative regimen is 2HRE/7HR, for which there is excellent clinical trial evidence.
The probability of resistance is higher in those patients who relapse and every effort must be made to obtain a specimen that can be cultured for sensitivities. That said, most patients who relapse do so with a fully sensitive strain and it is possible that these patients have not relapsed, but have instead been re-infected; these patients can be re-treated with the same regimen as before (no drugs need to be added to the regimen and the duration need not be any longer). The WHO recommends a regimen of 2SHREZ/6HRE when microbiology is not available (the majority of countries where TB is highly endemic). This regimen was designed to provide optimal treatment for fully sensitive TB (the most common finding in patients who have relapsed) as well as to cover the possibility of INH-resistant TB (the most common form of resistance found). Because of the lifelong risk of relapse, all patients should be warned of the symptoms of TB relapse upon finishing treatment and given strict instructions to return to their doctor if symptoms recur. Public health and health policy
As of 2010, India has more reported cases of TB than any other country. This is in part due to severe mismanagement of diagnosis and treatment of TB within the private health care sector of India that serves about 50% of the population. There are therefore calls for the private sector to engage in the public Revised National Tuberculosis Control Program that has proved effective in reducing TB amongst the patients receiving health care through the government.