Prevalence of preserved ratio impaired spirometry (PRISM) in patients undergoing spirometry in a medical college hospital

Background: Many patients come with respiratory symptoms of cough, expectoration and shortness of breath. They also exhibit history of risk factors like smoking etc. but on spirometry they do not meet spirometric criteria of chronic obstructive pulmonary disease (COPD). GOLD 2023 updates have considered such patients in the category of pre-COPD and preserved ratio impaired spirometry (PRISm) and advised to treat and follow these patients and try to prevent them from progressing to COPD. With this objective we tried to look for PRISm and its characteristics in our area. Material and methods: We analyzed the spirometric pattern of all the patients who underwent spirometry in our institution (GS Medical College & Hospital, Pilkhuwa) from January 2022 to December 2022. After applying inclusion and exclusion criteria, the patients were divided into three groups: (I) Normal Group: Patients having post bronchodilator FEV1/FVC ratio ≥ 0.7 and normal FEV1 and FVC. (II) PRISm Group: Patients having post bronchodilator FEV1/FVC ratio ≥ 0.7 but decreased FEV1 (< 80 %) and / or FVC (< 80 %). (III) Unrevealed COPD Group: Patients having post bronchodilator FEV1/FVC ratio < 0.7 irrespective of FEV1 and FVC. Data observed was compared among various groups and analyzed for various parameters. Results: A total of 986 patients underwent spirometry between 1st January 2022 and 31st December 2022. Of this, 302 patients were not considered for study because of exclusion criteria. 684 patients were considered for the study, of whom 261 (38.16%) had normal spirometry, 207 (30.26%) were in the PRISm group and 216 (31.58%) were found to have unrevealed COPD. Conclusion: Occurrence of PRISm is quite high (30.26%) in patients undergoing spirometry for various reasons in our area. Higher age and higher BMI may have contributed to the observations. Additionally, a considerable number of patients (31.58%) were found to have unrevealed COPD. Another finding is that smoking history is seen in more than 70% of male subjects in both PRISm and unrevealed COPD groups. However, the results need confirmation in more studies from different geographical areas. Keywords: spirometry; PRISm; COPD; pulmonary disease