TNAG-0655-FCO40-804-Development-of-medical-and-health-services-in-Hong-Kong-1977 — Page 11

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HONG KONG CHEST SERVICE/BMRC

at the end of their allocated regimen and were also available for bacteriologic assessment at 30 months.

Bacteriologic Status during Chemotherapy The bacteriologic status of patients during chemotherapy was given in the first report (2) and is summarized in table 1.

Patients with susceptible strains. The findings among patients with drug-susceptible strains be- fore treatment were that at 6 months all 137 SHZ patients and all but 2 (1 per cent) of 141 SH2Zз patients had a favorable bacteriologic status. In contrast, 5 (4 per cent) of 126 S2H2Z2 patients had an unfavorable status (defined as 3 or more positive cultures, at least one of which grew 5 or more colonies, out of a total of 6 cultures at months 4, 5, and 6). Of the patients with an un- favorable status, 1 of the SH3Z3 patients failed with a strain resistant to both isoniazid and streptomycin, and the other, whose strain at 6 months was resistant to streptomycin alone, be- came culture negative in the seventh month and had quiescent disease at the end of 9 months of chemotherapy. Two of the S2HZ2 patients failed with strains resistant to both isoniazid and streptomycin and the other 3 with strains resistant to isoniazid alone. Of 217 patients (70 SHZ, 69 S.H.Zg, 78 SqH2Z2) allocated to con- tinue chemotherapy to 9 months, only one failed during the last 3 months of chemotherapy, an S2H2Z2 patient with a strain resistant to both drugs.

Patients with resistant strains. Of 110 pa- tients with pretreatment strains resistant to isoniazid, to streptomycin or to both drugs, 30 per cent of 33 SHZ patients, 37 per cent of 41 SHZ3 patients, and 39 per cent of 36 SHZ patients had an unfavorable status at 6 months. Of the 60 patients (18 SHZ, 21 SHÖZ, 21 S2H¿Z») allocated to continue chemo- therapy to 9 months, 3 (1 SHZ, 2 S2H2Z2) failed during the last 3 months of chemotherapy.

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Of the 26 patients (6 SHZ, 10 SgHgZg, 10 SH2Z2) with pretreatment strains resistant to isoniazid alone 5 (2 SHZ, 3 S2H2Z2) (19 per cent) had an unfavorable bacteriologic status at 6 months, as did 16 (1 SHZ, 8 SH Z3, 7 SH„Z) (33 per cent) of 49 (15 SHZ, 18 SHÖZ, 16 S2HZ) with strains resistant to streptomycin alone and 18 (7 SHZ, 7 SHZ ̧, 4 S2H„Z1⁄2) (51 per cent) of 35 (12 SHZ, 13 SH„Z ̧, 10 S2HZ2) with strains resistant to both drugs.

Bacteriologic Relapse after Stopping Chemotherapy

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Bacteriologic relapse after stopping therapy was defined as at least 2 sputum cultures growing 10 or more colonies of M. tuberculosis in 2 separate months during a 3-month period. Only one patient relapsed after 24 months (when routine monthly sputum examinations stopped), and the relapse was confirmed by testing addi- tional sputum specimens. Additional specimens after 30 months were also obtained from pa- tients with no result available at 30 months.

Patients with susceptible strains before treat- ment. The bacteriologic relapse rates after stop- ping chemotherapy among patients with drug- susceptible strains before treatment are shown in table 2. After 6 months of chemotherapy, the relapse rates were high and similar on all 3 regi- mens. Of 167 patients (60 SHZ, 68 SH.Zg, 39 S2HZ) with a favorable status at the end of 6 months of chemotherapy who were available for bacteriologic assessment at 30 months (24 months after the end of chemotherapy), 35 (21 per cent) relapsed. In contrast, the relapse rates after 9 months of chemotherapy were low, only 10 (6 per cent) of the patients relapsing by 30 months (21 months after the end of chemo- therapy).

Nearly all the relapses, 29 of 35 in the 6- month series and 7 of 10 in the 9-month series, occurred within 6 months of stopping chemo- therapy. All the relapses were with strains fully susceptible to isoniazid and to streptomycin.

Patients with resistant strains before treat- ment. The bacteriologic relapse rates after stop- ping chemotherapy among patients with pre- treatment strains resistant to isoniazid, to strep- tomycin, or to both drugs are shown in table 3. The relapse rates were similar to those among patients with susceptible strains before treat- ment. After 6 months of chemotherapy, 7 (24 per cent) of 29 relapsed, and after 9 months 1 (4 per cent) of 26 relapsed.

Estimated Failure Rates during 30 Months Of 586 patients with pretreatment susceptibil- ity tests results available, 79 per cent had pre- treatment cultures susceptible to isoniazid and streptomycin, and 21 per cent had cultures re- sistant to one or both of these drugs. Estimates of the failure rates per 100 patients on each regi- men during chemotherapy and after chemother- apy up to 30 months were made by combining

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