BMJ No 7115 Volume 315
Papers Saturday 25 October 1997
Acute viral infections of upper respiratory tract in elderly people living in the community: comparative, prospective, population based study of disease burden
Karl G Nicholson, Julie Kent, Victoria Hammersley, Esperanza Cancio
Abstract
Objective: To evaluate the disease burden of upper respiratory infections in elderly people living at home.Design: Prospective surveillance of elderly people.
Intervention: None.
Setting: Leicestershire, England
Subjects: 533 subjects 60 to 90 years of age.
Main outcome measures: Pathogens, symptoms, restriction of activity, duration of illness, medical consultations, interval between onset of illness and medical consultation, antibiotic use, admission to hospital, and death.
Results: 231 pathogens were identified for 211 (43%) of 497 episodes for which diagnostic specimens were available: 121 (52%) were rhinoviruses, 59 (26%) were coronaviruses, 22 (9.5%) were influenza A or B, 17 (7%) were respiratory syncytial virus, 7 (3%) were parainfluenza viruses, and 3 (1%) were Chlamydia species; an adenovirus and Mycoplasma pneumoniae caused one infection each. Infections occurred at a rate of 1.2 episodes per person per annum (95% confidence interval 1.0 to 1.7; range 0-10) and were clinically indistinguishable. Lower respiratory tract symptoms complicated 65% of upper respiratory infections and increased the medical consultation rate 2.4-fold (chi2 test P<0.001). The median interval between onset of illness and medical consultation was 3 days for influenza and 5 days for other infections. Rhinoviruses caused the greatest disease burden overall followed by episodes of unknown aetiology, coronaviruses, influenza A and B, and respiratory syncytial virus.
Conclusions: Respiratory viruses cause substantial morbidity in elderly people. Although respiratory syncytial virus and influenza cause considerable individual morbidity, the burden of disease from rhinovirus infections and infections of unknown aetiology seems greater overall. The interval between onset of illness and consultation together with diagnostic difficulties raises concern regarding the role of antiviral drugs in treating influenza.
Introduction
Excess deaths have consistently been shown in elderly people
during the winter and have largely been attributed to influenza and low
temperature.(1) Until recently the possible contribution of
respiratory viruses other than influenza has attracted little
attention. During winter 1988-9 we observed the cocirculation of
various respiratory viruses, including influenza, in homes for elderly
people in Leicestershire.(2) The illnesses were
indistinguishable and were associated with lower re Population and study Subjects were seen at home as soon as possible after onset of
illness. Diagnostic specimens were collected as described
previously,(3) and symptoms were converted into
syndromes.(3-4) The illness was considered lower
r We studied 533 volunteers, 441 during the first winter and 439 during
the second.(3) The 257 men and 276 women were aged 63-90
(mean (SD) 72.6 (5.7)) years and 60-90 (71.8 (6.1)) years,
respectively, on recruitment. More men than women (207 (81%)
v 129 (47%), chi2 test P<0.001) were
either current or past smokers, but men and women were comparable with
respect to indications for influenza vaccine(5); vaccine
uptake; admission to hospital during the preceding 5 years; attendance
at a hospital outpatient department during the preceding 12 months; and
proportions consulting their medical practitioner during the preceding
12 months. The project was approved by the Leicestershire ethics
committee and signed informed consent was obtained from all
volunteers. Virology Estimates of disease burden In the present study illnesses not affecting the lower respiratory
tract or not causing impairment resulting in a change in normal
activities (confinement to bed or inability to cope with household
activities) were categorised "low morbidity" (category A). Episodes
affecting the lower respiratory tract or confining subjects to bed or
affecting their ability to cope with shopping, cooking, or washing were
considered "moderate" (category B); those resulting in admission to
hospital were category C, and deaths were category H. Episodes with
identification of more than one pathogen and pathogens causing fewer
than 10 episodes were excluded from the comparative analysis. Disease
burden values for categories A, B, and C were calculated from the
product of the number of cases and the median duration of illness
for that category divided by infant mortality equivalence values for
each category: 2,000,000 for category A, 100,000 for category B, and
80,000 for category C.(8) The disease burden from category
H was calculated from the number of deaths divided by an infant
mortality equivalence value of 3.(8) These values represent
a median of the perspectives of original committee members. The total
score for each pathogen is the sum of category subtotals. Statistics Clinical episodes Laboratory findings
Characteristics of respiratory viral illness
There were no pathognomonic features for any pathogen (table 2). The
median duration of the 291 episodes was 15 days (range 2-79). It was
longer in those with lower respiratory symptoms (median duration 16
days versus 12 days (Mann-Whitney test, P<0.0001)), which
occurred in 18/42 (43%; 95% confidence interval 28% to 58%)
coronavirus infections, 54/85 (64%; 54% to 74%) rhinovirus
infections, 93/134 (69%; 61% to 77%) unknown infections, 15/19
(79%; 61% to 97%) influenza infections, and 9/11 (82%; 59% to
100%) respiratory syncytial virus infections (chi2 13.26;
4df; P<0.02) (table 2). The incidence of sweats, myalgia, rigors,
earache, confinement to bed, capacity to carry out shopping, cooking or
washing, and domiciliary medical consultations also differed when
infections in table 2 were compared. Patients with influenza had high
rates of myalgia, sweats, and rigors; 63% (12/19) were confined to
bed, almost three quarters were unable to carry out shopping, cooking,
or washing, and lower respiratory symptoms were common (15/19; 79%).
Similarly most (9/11; 82%) of those with respiratory syncytial virus
had lower respiratory symptoms.
During the influenza A epidemic in 1993-4, 41% (7/17) of patients with
influenza confirmed by laboratory tests had myalgia with one or more
respiratory symptoms (sensitivity), and the percentage of all episodes
during the epidemic with myalgia and respiratory symptoms that were
confirmed as influenza A (the positive predictive value) was 28%
(7/25). The sensitivity was 29% (5/17) with the symptom complex of
myalgia, respiratory symptoms, and feverishness or sweats, and the
positive predictive value was 33% (5/15). The sensitivities remained
identical during non-epidemic periods, but the positive predictive
values fell to 7% (7/99) and 9% (5/58), respectively, with the above
symptoms. General practitioner review Deaths and admissions to hospital Disease burden values
Our subjects suffered a median of 1.2 acute "upper"
respiratory tract infections per annum, which is virtually identical
with rates reported for frail elderly people attending day care
units(9) and people aged 60 years and over living in the
community in Tecumseh.(10) In contrast with the results of
Falsey et al, who found respiratory syncytial virus to be the most
common cause of acute respiratory illness in elderly people attending
day care units,(9) we used the polymerase chain reaction
instead of viral cultures to identify rhinoviruses and an enzyme
immunoassay to identify infections with coronavirus OC43. We used a
less sensitive technique to identify respiratory syncytial virus, but
the same techniques to identify infections with influenza A and B and
coronavirus 229E.
Although we invited a randomly selected population of elderly people in
Leicestershire to take part in the study, participants may have been
more health conscious than non-participants and report symptoms and
consult their general practitioner for minor re Scope for antiviral treatment Burden of illness An intriguing observation in this study is the high incidence of
lower airways being affected during colds. Respiratory syncytial virus
and influenza were often complicated by lower respiratory illness, and
respiratory syncytial virus closely resembled influenza in terms of
domiciliary medical consultations. Interestingly, Falsey et al noted
similar clinical manifestations during 159 respiratory syncytial virus
and 221 influenza illnesses among elderly people living in the
community who were admitted to hospital with acute cardiopulmonary
conditions; they observed mortality of 10% and 6% for respiratory
syncytial virus and influenza, respectively, and concluded that
respiratory syncytial virus causes serious disease in these older
people.(22) The overall burden of respiratory syncytial
virus in our study was lower than that for influenza but is probably
underestimated because of the use of the complement fixation test to
diagnose respiratory syncytial virus. None the less, our observations
and those of other investigators(1)(9)(17)(22) provide
strong support for an assessment of candidate respiratory syncytial
virus vaccines in elderly people.
Unlike respiratory syncytial virus and influenza, coronaviruses caused
respiratory illness throughout the study. They were associated with
lower respiratory illness in more than 40% of patients and a quarter
consulted a medical practitioner and received antibiotics.
Coronaviruses represent the second most common cause of colds in adults
and, in our cohort, gave a higher disease burden value than influenza
or respiratory syncytial virus.
In our first report we speculated whether the burden of
rhinovirus infections in elderly people might approach that of
influenza.(3) In this study we found that a greater burden
came from rhinoviruses, pathogens that we were unable to identify, and
coronaviruses. Mortality increases considerably during the winter
months, when consultations for upper respiratory syndromes
increase.(1)(23) It is therefore highly plausible that
considerable morbidity and mortality from regular seasonal infections
with rhinoviruses, coronaviruses, and respiratory syncytial virus have
been overshadowed by less regular, readily recognisable epidemics of
influenza.
Leicester University School of Medicine,
Correspondence to: Dr
Nicholson
We gratefully acknowledge the support of volunteers who
participated in this study.
Funding: The study was supported by a grant from the
B
(Accepted 19 June 1997)
References
1 Nicholson K G. Impact of influenza and respiratory
syncytial virus on mortality in England and Wales from January 1975 to
December 1990. Epidemiol Infect 1996;116:51-63.
2 Nicholson K G, Baker D J, Farquhar A, Hurd D, Kent J, Smith S H.
Acute upper respiratory tract viral illness and influenza immunisation
in homes for the elderly. Epidemiol Infect
1990;105:609-18.
3 Nicholson K G, Kent J, Hammersley V, Cancio E. Risk factors for
lower respiratory complications of rhinovirus infections in the
community dwelling elderly: a prospective cohort study.
BMJ 1996;313:1119-23.
4 Monto A S, Bryan E R, Ohmit S. Rhinovirus infections in
Tecumseh, Michigan: frequency of illness and number of serotypes.
J Infect Dis 1987;156:43-9.
5 Department of Health. Immunisation against infectious
disease. London: HMSO, 1992.
6 Nicholson K G, Kent J, Ireland D C. Respiratory viruses and
exacerbations of asthma in adults. BMJ 1993;307:982-6.
7 Ireland D C, Kent J, Nicholson K G. Improved detection of
rhinovirus in nasal and throat swabs by semi-nested RT-PCR. J
Med Virol 1993;40:96-101.
8 Committee on Issues and Priorities for New Vaccine
Development. New vaccine development: establishing
priorities. Vol I. Diseases of importance in the United
States. Washington DC: National Academy Press, 1985:51.
9 Falsey A R, McCann R M, Hall W J, Tanner M A, Criddle M M, Formica
M A, et al. Acute respiratory tract infection in daycare centers for
older persons. J Am Geriatr Soc 1995;43:30-6.
10 Monto A S, Ullman B M. Acute respiratory illness in an American
community. JAMA 1974;227:164-9.
11 Monto A S, Cavallaro J J. The Tecumseh study of respiratory
illness. II. Patterns of occurrence of infection with respiratory
pathogens, 1965-1969. Am J Epidemiol 1971;94:280-9.
12 Monto A S, Sullivan K M. Acute respiratory illness in the
community. Frequency of illness and the agents involved.
Epidemiol Infect 1993;110:145-60.
13 Kellner G, Popow-Kraupp T, Kundi M, Binder C, Kunz C. Clinical
manifestations of respiratory tract infections due to respiratory
syncytial virus and rhinoviruses in hospitalized children. Acta
Paed Scand 1989;78:390-4.
14 Horn M E C, Brain E, Gregg I, Yealland S, Inglis J M. Respiratory
viral infection in childhood. A survey in general practice, Roehampton
1967-1972. J Hyg Camb 1975;74:157-68.
15 Tannock G A, Reid A L A, Gillett S M, Herd R, Gillett R S, Hensley
M J, et al. A study of respiratory infections in a healthy adult
population during the 1987 Australian winter. Fam Pract
1993;10:378-85.
16 Tyrrell D A J, Cohen S, Schlarb J E. Symptoms and signs in common
colds. Epidemiol Infect 1993;111:143-56.
17 Falsey A R, Treanor J J, Betts R F, Walsh E E. Viral respiratory
infections in the institutionalized elderly: clinical and
epidemiological findings. J Am Geriatr Soc
1992;40:115-9.
18 Thompson J, Fleet W, Lawrence E, Pierce E, Morris L, Wright P.
A comparison of acetominophen and rimantadine in the treatment of
influenza A infection in children. J Med Virol
1987;21:249-55.
19 Hall C B, Dolin R, Gala C L, Makovitz D M, Zhang Y Q, Madore P H, et
al. Children with influenza A infection: treatment with rimantadine.
Pediatrics 1987;80:275-82.
20 Wingfield W L, Pollack D, Grunert R R. Therapeutic efficacy of
amantadine HCI and rimantadine HCI in naturally occurring influenza A2
respiratory illness in man. N Engl J Med
1969;281:579-84.
21 Galbraith A W, Oxford J S, Schild G C, Watson G I. Study of
1-adamantanamine hydrochloride used prophylactically during the Hong
Kong influenza epidemic in the family environment. Bull
WHO 1969;41:677-82.
22 Falsey A R, Cunningham C K, Barker W H, Kouides R W, Yuen J B,
Menegus M, et al. Respiratory syncytial virus and influenza A
infections in hospitalized elderly. J Infect Dis
995;172:389-94.
23 Fleming D M, Cross K W, Crombie D L, Lancashire R J. Respiratory
illness and mortality in England and Wales. Eur J
Epidemiol 1993;9:571-6.
Subjects and methods
The study was conducted among people aged 60 years and older
during the winters of 1992-3 and 1993-4 in
Leicestershire.(3) During April to June 1992 we sent letters
to 800 of the 129,000 people aged 60 years and older who lived in
Leicestershire inviting them or their spouses, or both, to participate
in the study; the sample was randomly selected by the family health
services authority computer. We received 617 responses including 52
that were returned unanswered because of incorrect address, death, or
disinterest. A total of 441 subjects were recruited when the study
began in 1992. Ninety four of the 441 subsequently died, deteriorated,
or declined to take part during 1993-4, and an additional 92 subjects
were recruited in 1993 from the original respondents. Patients living
in residential care were excluded. Basic demographic data, medical and
drug history, and nose and throat swabs were collected at recruitment.
During surveillance periods each subject was contacted weekly by
telephone at a prearranged time. By using a questionnaire, volunteers
were asked whether an upper respiratory infection had occurred during
the previous week. When illness was reported, a record was made of date
of onset, symptoms,(3) incapacitation, medical
consultations, drug prescriptions, admission to hospital, and death.
Nasal swabs were placed high in the anterior nares and
throat swabs were passed firmly over the tonsils and pharynx. Swabs
were immediately placed in medium containing nutrient broth,
transported on dry ice, and stored at -70°C. Serum samples taken
during the acute and convalescent phase were stored at -20°C and
tested later by complement fixation tests for antibodies to adenovirus;
influenza A and B; respiratory syncytial virus; parainfluenza viruses
types 1, 2, and 3; Mycoplasma pneumoniae;
and Chlamydia psittaci. Haemagglutination inhibition
tests were also carried out for the identification of infections by
influenza type A. A fourfold rise in antibody titre was taken as
indicating infection. Enzyme linked immunosorbent assay was used to
detect rises in antibodies to coronaviruses 229E and
OC43.(6) Rhinoviruses in nose and throat swabs were
identified with a seminested reverse transcriptase polymerase chain
reaction.(6-7) Rhinovirus serotypes 14 and 1B were used as
positive controls; additional controls included baseline samples,
water, and transport medium. The appearance of a 202 base pair
amplification was taken to indicate rhinovirus infection.
We compared the disease burden of episodes for which diagnostic
specimens were provided with the method used by the US Institute of
Medicine's committee on issues and priorities for new vaccine
development for diseases of importance in the United
States.(8) The remit of the committee was to develop a
comprehensive approach to setting priorities for accelerated vaccine
development. In the decision making framework information on morbidity
and mortality are combined into a single numerical score, which permits
quantitive comparison of the burdens of morbidity and mortality rising
from different pathogens. Given that individual pathogens may cause a
spectrum of acute and chronic illness the committee estimated the
number of cases of different infections occurring in different
morbidity categories, namely: A - causing moderate localised pain, mild
systemic reaction, or impairment requiring minor change in normal
activities; B - causing moderate pain or moderate impairment requiring
moderate change in normal activities (for example, housebound or in
bed); C - requiring admission to hospital; D and E - relating to chronic
disability; F - relating to total impairment; G - relating to
reproductive impairment resulting in infertility; and H - relating to
death. The unit of comparison between categories was designated as the
"infant mortality equivalent."
Baseline variables in men and women and people with coronavirus,
rhinovirus, influenza, and respiratory syncytial virus infections and
episodes caused by unknown agents were compared by chi2
tests for discrete variables and Kruskall-Wallis tests for continuous
variables. Differences in the distributions of variables between
different infections were assessed by chi2 tests for
discrete variables and Kruskall-Wallis tests for continuous variables.
The Mann-Whitney U test was used to compare the intervals between onset
of illness and medical consultation for people with influenza and other
infections and duration of illness in those with and without lower
respiratory illness. Results
Volunteers completed 24,700 patient weeks of observation. We
identified 706 episodes, occurring at a median rate of 1.2 episodes per
person per annum (95% confidence interval 1.0 to 1.7; range 0-10) in
384 (72%) subjects. Symptoms were documented for 691 episodes.
Laboratory specimens were collected a median of four days after onset
of symptoms (range 1-21 days) for 497 (72%) of the 691 classified
episodes. Missing specimens occurred when there were delays in
reporting illness - notably, during Christmas, New Year, and Easter and
periods of travel.
Infection with 231 pathogens was identified for 211 (43%) of the
497 episodes (table 1). Of the 231, 121 were rhinoviruses (52%), 59
(26%) were coronaviruses, 22 were influenza A or B (9.5%), 17 were
respiratory syncytial viruses (7%), 7 (3%) were parainfluenza
viruses, and 3 (1%) were Chlamydia; an adenovirus and
Mycoplasma pneumoniae caused one infection
each.
Table 1 - Pathogens identified during 211 of the 497 upper respiratory
episodes for which laboratory specimens were available
Pathogen
Single infections
Coinfections
Total
Rhinovirus
107
14
121
Coronaviruses
45
14
59
Influenza A and B
19
3
22
Respiratory syncytial virus
11
6
17
Parainfluenza
6
1
7
Chlamydia spp
3
0
3
Mycoplasma pneumoniae
1
0
1
Adenovirus
1
0
1
Total
193
38
231
To avoid over-representation of symptoms of subjects with more
than one infection, we focused on infections in different subjects.
Table 2 shows the manifestations of 291 single infections occurring in
291 people with rhinovirus, coronavirus, influenza A and B, or
respiratory syncytial virus infection and infections of unknown
aetiology; and demographic features associated with episodes.
Coinfections and infections due to parainfluenza viruses, adenoviruses,
Mycoplasma pneumoniae, and Chlamydia
species are excluded because of their small number. Most subjects (284;
98%) had upper respiratory symptoms; 189 (65%) had lower respiratory
syndromes, and more than half (170; 58%) had systemic features. Table
2 shows that age, sex, and current smoking status of the groups were
comparable; though the prevalence of chronic medical conditions that
are indications for influenza vaccine differed among the groups
(chi2 11.09; 4df; P<0.05).
Table 2 - Demography and clinical characteristics of 291 acute upper
respiratory tract infections in 291 elderly people.Values are
numbers of patients (percentages; 95% confidence intervals) unless
stated otherwise
Feature
Coronavirus (n=42)
Influenza (n=19)
Rhinovirus (n=85)
Respiratory syncytial virus (n=11)
Unknown (n=134)
P value
Demography
No (%) of men
15
(36)10
(53)33
(39)7
(64)67
(50)NS
Median (range) age (years)
70.5
(60-87)70
(65-89)72
(61-88)70
(62-86)71
(61-86)NS
Current smoker
3
(7; 0 to 15)6
(32; 11 to 53)11
(13; 6 to 20)1
(9; 0 to 26)21
(16; 10 to 22)NS
Indication for influenza vaccine
25
(60; 45 to 75)4
(21; 3 to 39)50
(59; 49 to 70)4
(36; 8 to 64)67
(50; 42 to 59)<0.05
Symptoms
Upper respiratory:
Rhinorrhoea
30
(71; 57 to 85)12
(63; 41 to 85)61
(72; 63 to 82)9
(82; 59 to 100)95
(71; 63 to 79)NS
Sneezing
25
(60; 45 to 75)6
(32; 11 to 53)59
(69; 59 to 79)9
(82; 59 to 100)81
(60; 52 to 68)<0.05
Sore throat
24
(57; 42 to 72)11
(58; 36 to 80)55
(65; 55 to 75)9
(82; 59 to 100)71
(53; 45 to 62)NS
Dry cough
19
(45; 30 to 60)10
(53; 31 to 75)39
(46; 35 to 57)3
(27; 1 to 53)60
(45; 37 to 53)NS
Nasal congestion
22
(52; 37 to 67)9
(47; 25 to 69)39
(46; 35 to 57)8
(73; 47 to 99)59
(44; 36 to 52)NS
Hoarseness
19
(45; 30 to 60)5
(26; 6 to 46)35
(41; 31 to 52)3
(27; 1 to 53)53
(40; 32 to 48)NS
Purulent nasal discharge
12
(29; 15 to 43)6
(32; 11 to 53)26
(31; 21 to 41)6
(55; 26 to 84)33
(25; 18 to 32)NS
Any upper respiratory symptom
41
(98; 94 to 100)19
(100)83
(98; 95 to 100)11
(100)130
(97; 94 to 100)NS
Lower respiratory:
Purulent sputum
16
(38; 23 to 53)13
(68; 47 to 89)49
(58; 48 to 69)8
(73; 47 to 99)92
(69; 61 to 77)<0.01
Wheeze
9
(21; 9 to 33)8
(42; 20 to 64)25
(29; 19 to 39)7
(64; 36 to 92)45
(34; 26 to 42)NS
Pain on respiration
3
(7; 0 to 15)3
(16; 0 to 32)12
(14; 7 to 21)0
11
(8; 3 to 13)NS
Any lower respiratory symptom
18
(43; 28 to 58)15
(79; 61 to 97)54
(64; 54 to 74)9
(82; 59 to 100)93
(69; 61 to 77)<0.02
Systemic:
Headache
20
(48; 33 to 63)13
(68; 47 to 89)34
(40; 30 to 50)6
(54; 25 to 84)51
(38; 30 to 46)NS
Feverishness
8
(19; 7 to 31)9
(47; 25 to 69)20
(24; 15 to 33)3
(27; 1 to 53)28
(21; 14 to 28)NS
Sweating
4
(10; 1 to 19)9
(47; 25 to 69)14
(16; 8 to 24)3
(27; 1 to 53)24
(18; 12 to 25)<0.01
Myalgia
10
(24; 11 to 37)9
(47; 25 to 69)11
(13; 6 to 20)3
(27; 1 to 53)29
(22; 15 to 29)<0.05
Rigors
0
3
(16; 0 to 32)2
(2; 0 to 5)0
4
(3; 0 to 6)<0.02
Any systemic symptom
26
(62; 47 to 77)16
(84; 68 to 100)48
(56; 45 to 67)8
(73; 47 to 99)72
(54; 46 to 62)NS
Other:
Lacrimation
9
(21; 9 to 33)1
(5; 0 to 15)25
(29; 19 to 39)4
(36; 8 to 64)35
(26; 19 to 33)NS
Painful cervical adenopathy
3
(7; 0 to 15)1
(5; 0 to 15)8
(9; 3 to 15)1
(9; 0 to 26)16
(12; 7 to 18)NS
Faceache
3
(7; 0 to 15)2
(10; 0 to 23)10
(12; 5 to 19)2
(18; 0 to 41)11
(8; 3 to 13)NS
Earache
5
(12; 2 to 22)1
(5; 0 to 15)7
(8; 2 to 14)4
(36; 1 to 64)12
(9; 4 to 14)<0.05
Gritty eyes
3
(7; 0 to 15)1
(5; 0 to 15)8
(9; 3 to 15)0
13
(10; 5 to 15)NS
Any other symptom
15
(37; 22 to 52)5
(26; 6 to 46)37
(44; 33 to 55)5
(45; 16 to 74)61
(46; 38 to 54)NS
Impact
Confined to bed
10
(24; 11 to 37)12
(63; 41 to 85)24
(16; 8 to 24)4
(36; 8 to 64)32
(24; 17 to 31)<0.001
Unable to cope with washing, shopping or cooking
15
(36; 21 to 51)14
(74; 54 to 94)21
(25; 16 to 34)5
(45; 16 to 74)46
(34; 26 to 42)<0.01
Domiciliary consultation
3
(7; 0 to 15)5
(26; 6 to 46)6
(7; 2 to 12)3
(27; 1 to 53)12
(9; 4 to 14)<0.05
GP consultation
11
(26; 13 to 39)9
(47; 25 to 69)37
(44; 33 to 55)5
(45; 16 to 74)55
(41; 33 to 49)NS
Antibiotics
10
(24; 11 to 37)9
(47; 25 to 69)29
(34; 24 to 44)4
(36; 8 to 64)48
(36; 28 to 44)NS
NS = not significant (P>0.05)
Overall 117 (40%) of the 291 episodes were reviewed
medically and 100 (34%) were treated with antibiotics. Consultation
rates were higher for lower respiratory episodes than the remainder
(96/189 (51%) versus 21/102 (21%); chi2 25.14;
P<0.001). Comparison of the different infections revealed a difference
in domiciliary consultation rates (chi2 10.07; 4df;
P<0.05), though neither the combined practice and domiciliary
consultation rates nor the rates of antibiotic prescription
differed (table 2). Of 19 people with influenza A as sole pathogen,
nine were reviewed by a medical practitioner a median of 3 days after
onset of symptoms (range 1-14). Similarly, 108/272 (40%) coronavirus,
rhinovirus, respiratory syncytial virus and unidentified infections
were reviewed after a median of 5 days (range 1-29 days)
(Mann-Whitney U test, z=0.538; P=0.59) (table 2).
Altogether three of the 497 infections led to admission to
hospital and another was fatal. One woman died from chronic obstructive
airways disease exacerbated by a rhinovirus. A second woman with
chronic airways disease developed wheeze with sputum production and was
in hospital for 6 days with influenza A. Two patients with chronic
respiratory disease were admitted for 12 days and 4 weeks with
exacerbations after upper respiratory infections of unknown
aetiology.
Table 3 shows the disease burden values and the proportion of
cases in category A. Influenza had the smallest proportion of cases
with low morbidity (category A), but it ranked fourth overall after
rhinovirus infections, episodes of unknown aetiology, and
coronavirus infections.
Table 3 - Total disease burden values and ranking according to pathogen
responsible
Detail
Rhinovirus
Unknown
Coronavirus
Influenza
Respiratory syncytial virus
No of cases in category A/total
31/107
72/286
12/45
1/19
2/11
Total disease burden value
0.34773
0.03428
0.00467
0.00352
0.00200
Ranking
1
2
3
4
5
Discussion
As in other studies of colds we found rhinoviruses followed
by coronaviruses to be the most common pathogens,(6)(10-12)
and as in children,(13-14) healthy
adults,(15-16) and frail elderly
people(9-10)(17) we identified no pathognomonic features
for any pathogen. As amantadine and rimantadine are effective when
given within 24 to 48 hours after onset of influenza
A(18-21) we evaluated the sensitivity and positive
predictive value of influenzal symptoms. One or more respiratory
symptoms and myalgia occurred in only 41% of patients with influenza,
and only 28% of episodes with these features were confirmed as
influenza. The inclusion of feverishness or sweats as diagnostic
criteria reduced the sensitivity to 29% and increased the positive
predictive value to 33%. Temperature was not measured in our study,
but raised temperature occurs in similar proportions of influenza,
respiratory syncytial virus, rhinovirus, and coronavirus infections in
elderly people.(9)(17) We conclude that patients with
influenza will be difficult to target for antiviral chemotherapy
without a rapid, near-patient diagnostic test. Moreover patients with
influenza A in our study consulted their practitioner a median of 3
days after onset, suggesting that many elderly people with influenza
may seek medical attention too late for successful treatment.
To compare burden of illness caused by respiratory viruses we used
a method developed to set priorities for accelerated vaccine
development. The method was originally applied by using estimates of
disease incidence in the United States, but even with this and other
difficulties the system has been a useful tool. In our study we applied
the method to a small cohort, but disease incidence and morbidity were
monitored closely over two winters.
Key Messages
There are few data on the morbidity associated with respiratory
viruses other than influenza in elderly people Respiratory virus infections in elderly people are clinically
indistinguishable, and patients with influenza will be difficult
to target for antiviral treatment without a near patient diagnostic
test Overall, two thirds of elderly people with colds and four fifths
of those with influenza and respiratory syncytial virus can be
expected to develop lower respiratory illness Although influenza and respiratory syncytial virus cause substantial
morbidity in elderly people, the disease burden from rhinovirus
infections and colds of unknown aetiology is greater overall Most elderly patients seek medical attention beyond 48 hours when
the benefits of antiviral treatment of influenza remain unproved
Department of Microbiology and Immunology,
Leicester LE1
9HN
Karl G Nicholson, senior lecturer in
infectious diseases
Julie Kent, research
assistant
Victoria Hammersley, research
assistant
Esperanza Cancio, postdoctoral
research fellow
Conflict of interest: None.
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