The causes and consequences of seasonal variation in COPD exacerbations

Figures & data

Figure 1 Proportion of patients reporting an exacerbation in the (A) northern or southern regions, and in (B) the tropics, averaged over 1 calendar year.

Notes: Reproduced with permission of the European Respiratory Society. Eur Respir J January 2012; 39:38–45; published ahead of print July 7, 2011, doi:10.1183/09031936.00194610 © European Respiratory Society.¹¹

Figure 2 Diary-card data collected from the London COPD cohort between November 1995 and November 2012.

Notes: Points are the percentage of patient-reporting activity, worsening of respiratory symptoms or onset of exacerbation on days within 1°C, or average peak expiratory flow rate on those days.
Abbreviations: COPD, chronic obstructive pulmonary disease; PEFR, peak expiratory flow rate.

Figure 3 Seasonality of COPD mortality, by age.

Notes: Mean daily deaths per million population (mortality) for men and women aged 65–74, 75–84, and 85+ years for each month between 1976 and 2012 in England and Wales from COPD (coded with the ninth and tenth International Classification of Diseases [ICD] as ICD-9 490–492, 496 for years before 2001, and ICD-10 J40–J44 thereafter) were extracted from death-registration data supplied by the Office of National Statistics (ONS). To be compatible with deaths before 1983 and after 1993, daily deaths from COPD were divided by 0.940 to adjust for differences in mortality-coding instructions in the intervening years. Deaths classified using the ICD-10 (2001–2012) were divided by 0.966 to allow for differences between the ICD-9 and ICD-10. Deaths per day per million population were obtained after dividing daily deaths by daily population estimates obtained by fitting a fifth-order polynomial to yearly estimates of the populations from the ONS from census data.

Abbreviation: COPD, chronic obstructive pulmonary disease.

Figure 4 Time-series analysis showing the time courses of respiratory mortality following a cold day.

Notes: M RES describes the increase in mortality per 1°C fall in temperature. The y-axis is the regression coefficients of mortality on temperature on days before and after day 0. The horizontal line is the means of values at lag −30 to −16 days. *Peak value and significantly different from zero, P<0.001. Reproduced from J Epidemiol Community Health, Early increases in ischaemic heart disease mortality dissociated from and later changes associated with respira tory mortality after cold weather in south east England, Donaldson GC, Keatinge WR, 51(6),643–648, copyright 1997, with permission from BMJ Publishing Group Ltd.⁴⁰
Abbreviation: M RES, respiratory disease mortality.

Table 1 Prevalence of respiratory viruses at COPD exacerbation

Respiratory virus	McManus et al^Citation49	Seemungal et al^Citation50	Beckham et al^Citation51	Rohde et al^Citation52,†	Ko et al^Citation48
Exacerbations, n	136	168	194	85	262
Virus-positive exacerbations (%)	50 (36.8%)	66 (39.2%)	81 (41.8%)	48 (56.5%)	58 (22.1%)
Viruses detected, n	56	77	88	59	56
Human rhinovirus*	57%	50%	44%	36%	14%
Influenza A	5%	8%	16%	25%	32%
Influenza B	0	4%	2%	7%	11%
Corona	2%	9%	18%	0	21%
Parainfluenza	9%	1%	10%	10%	7%
Adenovirus	18%	1%	1%	0	2%
RSV	6%	25%	8%	22%	11%
Metapneumovirus	4%	1%	0	0	2%

Notes:

* Percentages for viral types are calculated as the percentage of viruses detected; totals may therefore exceed 100%, as some samples had dual infection and/or rounding;

† data combined for serology and polymerase chain reaction.

Abbreviations: COPD, chronic obstructive pulmonary disease; RSV, respiratory syncytial virus.

Figure 5 Weekly data on laboratory reports of respiratory virus isolation by the Health Protection Agency/Public Health England and National Health Service hospital laboratories in England and Wales.

Notes: Data points are the average for that week over years 1980–2013. The y-axes show the number of viruses isolated per week. Adapted from Respiratory infections: laboratory reports 2014 [homepage on the internet]. Public Health England; 2014 [updated September 5, 2014]. Available from: https://www.gov.uk/government/publications/respiratory-infections-laboratory-reports-2014. Accessed September 24, 2014. Contains public sector information licensed under the Open Government Licence v2.0.⁷⁷

Figure 6 Percentage of patients going outside the home against the daily mean temperature throughout the year.

Notes: Points are at the center of each 1°C interval; vertical lines are at 2.5°C and 20.5°C. Reproduced with permission from the American College of Chest Physicians from Donaldson et al.¹⁴

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