Low peak expiratory flow and subsequent first self-report of recognized lung disease: Person-disjoint replication and spirometric benchmarking in HRS and ELSA.

BACKGROUND: Low peak expiratory flow (PEF) may precede the first self-report of recognized lung disease, but cross-cohort consistency and incremental value are uncertain.

METHODS: We analysed Health and Retirement Study (HRS) discovery and prespecified person-disjoint replication samples and the English Longitudinal Study of Ageing (ELSA). The estimand linked baseline PEF to the first subsequently observed self-report of recognized lung disease, not biological onset. HRS used a prespecified nominal lower-decile z score and ELSA an empirical lower decile. Participant-clustered models adjusted for demographic, clinical and functional factors. Weighting and a stroke comparator were sensitivity analyses. Post-hoc ELSA benchmarking compared PEF with FEV1 and FVC using person-disjoint cross-validation and full-pipeline bootstrap sensitivity.

RESULTS: Models included 18,510 HRS discovery windows (320 reports), 11,424 replication windows (188), and 8,634 ELSA person-waves (95). Low PEF was associated with first report in discovery (odds ratio [OR] 3.36, 95% confidence interval [CI] 2.54-4.45), replication (3.14, 2.19-4.49), and ELSA (3.77, 2.36-6.01). Weighted estimates were similar; stroke associations were weaker or null. After adjustment for separate FEV1 and FVC indices, the continuous-PEF OR was 1.04 (0.90-1.20). In 1,584 fixed-horizon participants (95 events), AUCs were 0.650 for covariates, 0.684 with PEF, 0.745 with FEV1 and FVC, and 0.739 with all three. Full-pipeline bootstrap sensitivity found no clear incremental evidence beyond FEV1 and FVC. Across differing horizons, low-PEF rules identified fewer than one-third of reports in HRS replication and ELSA.

CONCLUSIONS: Lower PEF was associated with a subsequent first observed lung-disease report; cohort-specific low-PEF rules identified fewer than one-third. In exploratory fixed out-of-fold predictions, PEF improved average precision and prediction error over covariates; no clear incremental evidence remained after FEV1 and FVC. Same-protocol collection does not establish a peak-flow-only pathway.