Background: The International Prognostic Score (IPS-7) is widely used for risk stratification in classical Hodgkin lymphoma (cHL), but its applicability in low- and middle-income countries remains unclear. This study aimed to externally validate IPS-7 and assess its prognostic performance for overall survival (OS) in an Indonesian cohort.

Methods: This retrospective cohort study included patients aged ≥15 years with histologically confirmed cHL across Ann Arbor stages I–IV, treated at a tertiary cancer referral centre between January 2019 and June 2022. IPS-7 was determined at diagnosis. OS at 1–3 years was estimated using Kaplan–Meier and compared across risk groups using the log-rank test. Univariate Cox regression evaluated each IPS-7 component, and model discrimination was assessed using Harrell’s C-index.

Results: Ninety-eight patients were analysed, with 34 events (34.7%). Median OS for low-, intermediate-, and high-risk groups was 42, 30, and 16 months, respectively. OS was 88%, 80%, and 74% at 1–3 years in the low-risk group; 70.5%, 67.4%, and 54.5% in the intermediate group; and 35.1% at 1 year in the high-risk group. Survival differed significantly among risk groups (log-rank p = 0.015). No single IPS-7 variable was significant on Cox analysis. Harrell’s C-index for IPS-7 in the overall cohort was 0.547 (95% confidence interval (CI) 0.394–0.701), indicating poor to borderline discrimination. In an exploratory analysis, IPS-3 showed comparable performance, with a C-index of 0.590 (95% CI 0.326–0.855). In the advanced-stage subgroup (Ann Arbor stage III–IV), both IPS-7 and IPS-3 demonstrated moderate discriminative ability, with C-index of 0.605 (95% CI 0.445–0.765) and 0.603 (95% CI 0.423–0.783), respectively. Conclusion: IPS-7 significantly stratified OS, with limited discrimination in the overall mixed-stage cohort but modest performance in the advanced-stage subgroup, supporting its cautious use for baseline risk stratification in resource-limited settings.