This institutional based, observational prospective study was undertaken in Department of Medicine, Maulana Azad Medical College, Lok Nayak hospital, New Delhi.

Inclusion criteria: The diagnosed cases of COPD patients who presented in acute exacerbation i.e., acute worsening of respiratory symptoms that results in dire need of additional therapy as per GOLD Guideline, to the Medicine Emergency as well in Outpatient Department of the institute were included in this study.

The study data was compiled over duration of 6-8 months in the year 2013-14. Index study was conducted after prior approval no F.11/IEC/MAMC/2013-14/53 of Institution Ethics Committee Maulana Azad Medical College.

The sample size was calculated using standard formula: n=Z² P (1-P)/d² (Where, n=sample size, z=z statistic for the level of confidence, P=expected prevalence of COPD i.e., 9% [2] and d=allowable error). The study projected a 95% confidence level with ±5% allowable error, for the study. The sample size needy was ~140 but, taking into consideration forthcoming losses in participants’ number; a total of 180 patients of COPD were enrolled in the study.

Informed consent was taken from all the patients. All the patients were subjected to complete history and physical examination and particulars of the patients such as name, age, sex, pack years of smoking, duration of COPD (if previously diagnosed), medications being used, number and frequency of past ICU/In-patient admissions, treatment compliance, etc., were noted in a pre-structured proforma and a compiled data extended excel-sheet was made.

A series of basic biochemical investigations and cx-ray, ECG were carried out. Body mass index was calculated. Spirometry test was performed after stabilisation.

CAT [7] and CCQ questionnaires [8] were filled-up within 48 hours of admission, after 1 week and at 4-6 weeks. mMRC grading was done based on patient’s symptoms at admission, 1 week and after 4-6 weeks.

Exclusion criteria: Patients who were having some pre-existing non-respiratory illnesses such as anaemia, cardiac illness, chronic kidney disease and chronic liver disease were excluded from this study. Patients having previously diagnosed respiratory entities such as pneumonia, diffuse bronchiectasis, and interstitial lung disease were also excluded.

Of the 180 Inpatient COPD patients enrolled in the study, 21 patients died due to the severity of their illness during in-hospital stay; 23 patients were lost to follow-up as they never visited centre again once discharged [Table/Fig-1]. Thus, 136 patients were followed-up to 4-6 weeks and the change in CAT, CCQ and mMRC scores were analysed.

The absolute frequencies and percentages were used to describe the quantitative variables. Furthermore, cumulative frequencies and percentages were used for ordinal qualitative variables. The description of quantitative variables was performed using the mean, standard deviation, median and quartiles. The correlation between quantitative variables was performed using the Spearman’ correlation coefficient. A p-value of <0.05 was considered significant. The pearson’s correlation coefficient (r) has the values starting from -1 to 1. The relationship between two variables is strong when value are >0.7.

The mean age of the index study group was 59.68 years (range: 32-82 years). The mean age of males was 58.61 years and the females was 63.05 years. 78% of the COPD patients were male as shown in [Table/Fig-1]. Out of 180 patients, majority had exposure to bidi smoke. Some of the patients were smokers as well having exposure to challah/biomass fuel combustion.

The mean±SD values of CAT, CCQ and mMRC scores at admission, after 1 week and after stabilisation (at 4-6 weeks) was calculated as shown in [Table/Fig-2]. These scores were calculated taking into account only the effective number of participating patients at subsequent point of time respectively i.e., at admission, 1 week and 4-6 week.

The respective changes of CAT, CCQ and mMRC scores from admission to 1 week and from admission to 4-6 weeks were calculated along with the estimation of statistical significance, as shown in [Table/Fig-3].

Correlations coefficient among CAT, CCQ and mMRC scores showed that correlation increases as the COPD patients improved towards a stable state (6 weeks) compared with at admission and 1 week. Correlations among change in CAT, CCQ and mMRC scores from admission to 1 week and after stabilisation (6 weeks) showed that correlation increased as the COPD patients improved to stable state compared with admission and at 1 week, respectively [Table/Fig-4].

Analysis of CAT score showed that the variation in the CAT score between exacerbation onset and recovery was not dependent on the score at exacerbation (p-value 0.629). However, there was good correlation between variation in the CCQ score from exacerbation to stabilisation with score at exacerbation (p-value of <0.001) and weak correlation between variation in the mMRC score from exacerbation to stabilisation with score at exacerbation (p-value of <0.05).

The study conducted, is one of its kind using longitudinal comparison of CAT, CCQ and mMRC scores in Indian COPD population. The authors compared the data majorly with studies conducted previously using similar parameters and methodology. The mean age of index study group was lower compared to similar studies done by Miravitlles M et al., and by Lee S et al., [10,11]. In this study, major stake is male participants (78%) attributing to prevalent smoking habit compared to females, as described in previous studies done by Miravitlles M et al., and Jindal SK [10,12]. However, worldwide the pattern of smoking and tobacco consumption is changing as evidenced by increasing COPD prevalence among females, in various epidemiological data [13-16].

Mean BMI calculated in index study was 24.79 kg/m². Demographic data including BMI thus included, it being an independent negative determinant of COPD survival, as advocated by Chailleux E et al., and Yang L et al., [17,18]. In this study, majority of the participants were smokers (bidi, cigarette or household/occupational biomass fuel exposure) similar to study conducted by Jindal SK et al., [19].

A statistically significant change of mean CAT score at exacerbation, at 1 week and after 6 weeks was found in the index study; advocating its high predictability in assessing health status. Mean CAT score in stable COPD was much lower than in exacerbation as shown by Jones PW et al., and Agusti A et al., [20,21]. An epidemiological, prospective, multicentre study by Miravitlles M et al., included 476 COPD patients with a CAT score of 22.8 points in their inpatients, which was significantly reduced to 12.4 after recovery from the acute episode [10]. The difference between CCQ score at exacerbation and at 1^st week and between CCQ score at exacerbation and at 4^th-6^th week (after stabilisation) were found to be statistically significant.

This suggests that CCQ score is a good predictor of health status, as there was significant reduction of CCQ score after recovery at 1 week and after stabilisation at 4-6 weeks. In a study done by Miravitlles M et al., in Spain, statistically significant improvement in the CCQ score from exacerbation to recovery was observed [10]. In a multicentre prospective cohort study with 121 patients done by Trappenburg JC et al., change in CCQ total scores were significantly higher during exacerbation, 3.5±0.69 compared to -0.4±0.37 in stable state (p<0.001) [22]. The mean change in CCQ-total score was decreased significantly after stabilisation (Δ-CCQ-score: -2.6, 95% CI: -4.3 to -0.9, p=0.001).

In the index study, the difference between mMRC score from exacerbation and at 1 week was 0.93±0.469 (p<0.001) and between exacerbation and at 4-6 weeks was 1.83±0.719 (p<0.05). To the best of our knowledge, the study is the first of its kind in assessing the course of health status of COPD patients from exacerbation to recovery using mMRC score. Some previous studies disregarded the frequent usage of mMRC scale in COPD classification as a surrogate to CAT score, attributing its capability of assessing only one parameter i.e., breathlessness [9,23]. However, results showed mMRC scale in good correlation with exacerbation as a well stable state.

At exacerbation, a good correlation was found between CAT and CCQ scores and CAT and mMRC scores, respectively. Similarly, correlation between CCQ and mMRC scores at exacerbation also found to be significant. There was strong correlation between CAT and CCQ score at 1 week and at 4-6 weeks. Correlation between CAT and mMRC at 1 week was weak (p<0.001) while at 4-6 weeks was positive [Table/Fig-3,4]. Correlation between CCQ and mMRC score at 1 week was significant whereas it was much stronger at 4-6 weeks.

These results suggested that both CAT and CCQ are measuring similar factors and can be used reliably and interchangeably in this context. Though mMRC measures only breathlessness, shortness of breath is the most frequent symptom reported by patients with long lasting COPD. The presence of dyspnoea significantly reduces the quality of life, leads to inability to work in a productive manner. So, the study can use mMRC as a preliminary aid to assess the health status and clinical course in all COPD patients.

As far as CAT and CCQ are concerned, the study showed similar results with the studies done by Miravitlles M et al., in Spain and by Ringbaek T et al., [10,24].

In a study done by Kim S et al., the classification of COPD on the basis of mMRC or CAT score was not identical [25]. The mMRC score is the most strongly correlated with dyspnea item of CAT. However, this study supported the use of this score in predictive analysis of COPD.

There was a good correlation between change in CAT and change in CCQ scores from exacerbation to 1 week and from exacerbation to 4-6 weeks (r=0.756 and 0.737, respectively; p<0.001). A significant correlation was observed between change in CAT and change in mMRC scores from exacerbation to 1 week and from exacerbation to 4-6 weeks (r=0.422 and 0.746, respectively; p<0.001). Correlation between change in CCQ and change in mMRC scores from exacerbation to 1 week and from exacerbation to 4-6 weeks were also significant (r=0.513 and 0.638, respectively; p<0.001 for both).

Similar study conducted by Miravitlles M et al., found an acceptable correlation between the change (exacerbation-recovery) scores in both questionnaires (R=0.594; p<0.0001) [10].

Spirometric assessment was also done in the index study once the admitted patients attained a comfortable state varied from Day 3 to Day 5 to perform the test. The severity of COPD stage reported in spirometry (using FEV1 as per GOLD parameters) correlated neither with the CAT, CCQ and mMRC scores neither at admission nor with the course of recovery of the patients from exacerbation to stabilisation. This result was consistent with the study done by Jones PW et al., [23]. They illustrated that, within any given COPD category as per GOLD staging, patients may have anything between relatively well preserved to very poor health status.

In the index study, it was seen that a worse score at exacerbation onset leads to a significant improvement in CAT and CCQ after recovery in terms of absolute figures. Findings of the study conducted by Miravittles M et al., defied this study’ findings probably because they enrolled both inpatients and out patients in their study but in this study only inpatients were enrolled which were having more debilitating condition [10].

Sample size of the study was in accordance with the global as well local prevalence [2,3]. However, the patients included here were of the same race; COPD patients of different races may have different outcomes. All the comparative scores have an in-built subjective component within, landing in result variability. In the index study and its statistical analysis, confounding factors as comorbidities like CAD which may have a negative impact on disease outcome were not ruled out completely. Lastly, the data thus obtained might be biased by the single medical-centre-based patients rather than population based patient inclusion.

Comprehensive questionnaires such as CAT and CCQ are much detailed and suitable for prediction of outcome of acute exacerbation of COPD. Additionally, they also have advantage of simplicity for the patient. Use of mMRC scale which measures the severity of breathlessness is still widespread because of easy applicability. Therefore CAT, CCQ and mMRC scores can be used interchangeably as better objective scales, attributing to their inter-equality and reliability.