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ASSESSING THE SENSITIVITY OF SURVEILLANCE FOR PNEUMONIA IN RURAL

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					                                       PNEUMONIA S URVEILLANCE   IN   THAILAND


    ASSESSING THE SENSITIVITY OF SURVEILLANCE FOR
            PNEUMONIA IN RURAL THAILAND
             Shadi Chamany 1,2, Channawong Burapat 3, Yupapan Wannachaiwong 4,
        Khanchit Limpakarnjanarat 3, Nakorn Premsri 5, Elizabeth R Zell 6, Scott F Dowell 3,10,
                            Daniel R Feikin 7,8 and Sonja J Olsen 3,9

    1
        Epidemic Intelligence Service and Preventive Medicine Residency Program, Office of
    Workforce and Career Development (OWCD), Centers for Disease Control and Prevention
    (CDC), Atlanta, GA; 2Division of Health Promotion and Disease Prevention, New York City
     Department of Health and Mental Hygiene, New York, NY, USA; 3International Emerging
   Infections Program, Thailand Ministry of Public Health-US CDC Collaboration, Nonthaburi,
    Thailand; 4Sa Kaeo Provincial Health Office, Ministry of Public Health, Sa Kaeo, Thailand;
 5
   Social Medicine Department, Sa Kaeo Crown Prince Hospital, Sa Kaeo Province, Thailand;
    6
      Biostatistics and Information Management Branch, Division of Bacterial Diseases (DBD),
     National Center for Immunization and Respiratory Diseases (NCIRD), CDC, Atlanta, GA;
7
  Respiratory Diseases Branch, DBD, NCIRD, CDC, Atlanta, GA, USA; 8International Emerging
  Infections Program, Kenya-US CDC Collaboration, Kisumu, Kenya; 9Global Activities Team,
     Division of Emerging Infections and Surveillance Services, NCPDCID, CDC, Atlanta, GA;
       10
          Division of Global Preparedness and Program Coordination, Coordinating Office of
                                Global Health, CDC, Atlanta, GA, USA

         Abstract. We conducted a household survey among Sa Kaeo residents to characterize self-
         reported health-seeking behavior for pneumonia and the proportion of individuals who seek
         care at a hospital to determine the coverage of a surveillance system. A 2-stage cluster sample
         was used to select households. A case of pneumonia was defined as a self-reported history of
         cough and difficulty breathing for at least 2 days or being given a diagnosis of pneumonia by a
         healthcare provider in the 12-month period beginning February 1, 2002, and ending January
         31, 2003. Interviewers administered a structured questionnaire that asked about clinical ill-
         ness and utilization of healthcare services. Among 1,600 households, 5,658 persons were
         surveyed, of whom 62 persons met the case definition. Of the 59 persons with complete data,
         53 (90%, 95% CI: 79-96) sought medical care and 47 (80%, 95% CI: 67-89) sought care at a
         hospital facility in the province. Neither distance nor cost was reported as a barrier to seeking
         care. Most individuals with self-reported pneumonia sought care at the hospital level. Popula-
         tion-based surveillance can provide reliable estimates of hospitalized, chest radiograph-con-
         firmed pneumonia in Sa Kaeo if adjustments are made to account for the proportion of indi-
         viduals who access a hospital where radiologic assessment is available.

                 INTRODUCTION                               tries, particularly among persons less than 5
                                                            years of age (WHO, 1999b; Williams et al,
    Pneumonia is one of the leading causes                  2002). The most common bacterial agents
of morbidity and mortality in developing coun-              causing pneumonia are Str eptococcus
Correspondence: Dr Sonja J Olsen, 1600 Clifton              pneumoniae (pneumococcus) and Haemophi-
Road, MS C-12 Atlanta, GA 30333, USA.                       lus influenzae (Shann, 1986; Wall et al, 1986;
Tel: 404-639-7883; Fax: 404-639-3106                        Ghafoor et al, 1990; Forgie et al, 1991a,b;
E-mail: SOlsen@cdc.gov                                      Adegbola et al, 1994). While it is estimated


Vol 39 No. 3 May 2008                                                                                        549
                              SOUTHEAST ASIAN J TROP MED PUBLIC H EALTH


that pneumococcus and H. influenzae contri-          illness and seeking care. The results from this
bute to over 1 million deaths annually among         survey will ultimately be used to adjust data
young children in developing countries (WHO,         on the incidence of hospitalized, chest radio-
1999a, 2006, 2007), vaccines have been               graph-confirmed pneumonia from the surveil-
shown to dramatically decrease the incidence         lance system to generate accurate estimates
of these diseases in both developed and de-          of the burden of pneumonia in Sa Kaeo, Thai-
veloping countries (Black et al, 1991; Lagos         land.
et al, 1996; CDC, 2000; Whitney et al, 2003).
      In 2002, an active, population-based sur-              MATERIALS AND METHODS
veillance system for hospitalized, chest radio-
graph-confirmed pneumonia was introduced                  Sa Kaeo is a rural, agrarian province lo-
in Sa Kaeo Province, Thailand, supplement-           cated in the eastern part of Thailand, border-
ing the pre-existing passive surveillance sys-       ing on Cambodia. In 2001, the total popula-
tem for pneumonia (Olsen et al, 2006). The           tion of the province was 438,557 persons,
goals of this active surveillance system are to      served by 8 hospitals. In 2002, the provincial
obtain accurate estimates of disease burden          health office estimated the number of regis-
and determine the primary etiologies of pneu-        tered and unregistered migrant workers to be
monia in order to guide policy decisions such        approximately 25,000. As of the 1999 cen-
as new vaccine introduction. Because this            sus, there were 610 villages throughout the
surveillance system is hospital-based and the        province, the number of households within
majority of radiograph machines in this pro-         each village ranging from 15 to 2,978. The
vince are found in hospitals, the coverage of        average monthly household income is 6,958
the surveillance system is contingent upon the       baht or US$ 155 (Anonymous, 2001). Health-
proportion of individuals with pneumonia who         care services are sought from a variety of per-
seek care at the hospital and subsequently           sons and places, including village health vol-
receive a chest radiograph.                          unteers, pharmacists, drug sellers (people who
     In 2003, we conducted a household sur-          sell medications in stores not designated as
vey to determine what proportion of indivi-          pharmacies), health centers, private physician
duals living in Sa Kaeo Province who had self-       offices, and hospital facilities including outpa-
reported pneumonia in the previous year              tient departments, emergency departments,
sought care at the hospital level to address         and inpatient departments.
the sensitivity of our surveillance system to              A 2-stage cluster sample was used to se-
identify possible cases. The second aspect of        lect households for the survey. The necessary
being captured in the system, receiving a chest      sample size was calculated using the 2002 in-
radiograph, is addressed elsewhere (Olsen et         cidence of pneumonia from the passive sur-
al, 2006). In addition, because health-seek-         veillance system (1.9 cases per 1,000 persons)
ing behavior may be influenced by character-         and a 95% confidence interval around this es-
istics such as sex, income, and education            timate. This sample size was inflated to ac-
(Chen et al, 1981; Sen, 1984; Das Gupta,             count for an estimated non-response rate of
1987; Ganatra and Hirve, 1994; Srivastava            20% based on previous household surveys
and Nayak, 1995; Konradsen et al, 1997;              with response rates of 82% and 94% (Win-
Okanurak et al, 1997; Goldman et al, 2002;           ston and Patel, 1995; Ng et al, 2002). This
D’Souza, 2003; Pillai et al, 2003), we also ex-      sample size was further inflated by a factor of
amined the presence of any association               1.5 as the estimated design effect to account
among these characteristics and self-reported        for the clustering of pneumonia cases by


550                                                                         Vol 39 No. 3 May 2008
                                     PNEUMONIA S URVEILLANCE   IN   THAILAND


                                                                             for at least 6 of the preceding
                                                                             12 months, including persons
                                                                             who were deceased at the
                                                                             time of the interview. The
                                                                             caretaker for a household was
                                                                             the person responsible for the
                                                                             health of members in the
                                                                             household and/or a person
                                                                             who takes care of the children
                                                                             for more than 2 hours a day.
                                                                             A “no response” household
                                                                             was defined as one in which
                                                                             there was no answer on 3
                                                                             separate visits at least 24
                                                                             hours apart. A case of pneu-
                                                                             monia was defined as a self-
                                                                             reported history of a cough
                                                 X    Selected village       and difficulty breathing for at
                                                 –    District boundaries    least 2 days or being given a
                                                                             diagnosis of pneumonia by a
                                                                             healthcare provider in the 12-
                                                                             month period beginning Feb-
Fig 1–Villages selected for inclusion into a house-                          ruary 1, 2002, and ending
      hold survey examining health-seeking pat-
                                                                             January 31, 2003, in an indi-
      terns for pneumonia, Sa Kaeo Province, Thai-
                                                                             vidual living in Sa Kaeo Prov-
      land, June 2003.
                                                                             ince. This case definition of
                                                                             pneumonia was adapted from
village and by household. The final sample size              the World Health Organization (WHO) verbal
was 1,600 households. Using probability pro-                 autopsy report for severe pneumonia in chil-
portional to size, 40 villages were randomly                 dren, using questions that were moderately
selected from the total of 610 villages in Sa                sensitive and specific for pneumonia (WHO,
Kaeo Province in the first stage based on the                1999c).
number of households in each village (Fig 1).                   A 2-part questionnaire was used to col-
In the second stage, a sample of 40 house-                lect information from individuals within each
holds was selected within each village. The               household. The first part included demo-
start household for each village sample was               graphic information about the household for
identified by randomly selecting 1 house num-             all the individuals living in that household. Two
ber from a list of all house numbers for that             screening questions were asked of each indi-
village. Subsequent households were selected              vidual in the household to identify persons who
as the interviewers walked to the next near-              had pneumonia using the case definition de-
est household following a series of standard-             scribed above. The second part was a detailed
ized instructions given to each team of inter-            clinical questionnaire for each individual who
viewers.                                                  met the case definition for pneumonia. Prior
     A household member was defined as any                to the beginning of the survey, the question-
individual who had slept in a given household             naire was pilot-tested in Thai, revised in


Vol 39 No. 3 May 2008                                                                                   551
                               SOUTHEAST ASIAN J TROP MED PUBLIC H EALTH


English, and translated back into Thai for use        ing design was used in the first stage of sam-
in the actual interviews.                             pling (probability proportional to size at the
      Ten Sa Kaeo provincial health officers          village level) and each individual in the house-
were trained during a 3-day session to ensure         hold was interviewed, each observation
standard interview techniques. Interview              (household or individual) had an equal weight
teams were made up of 2 health officers and           of 1 in all analyses. When possible, compari-
a village health volunteer who visited house-         sons between groups were made using SAS-
holds in the villages to which they were as-          Callable SUDAAN (SUDAAN Version 8.0, RTI
signed. Visits were made during the day, in           International, Research Triangle Park, NC) to
the evenings, and on weekends to optimize             account for clustering at the village and house-
response rates. The primary caretaker served          hold level. The significance of association for
as a proxy for individuals less than 7 years of       each variable was determined using the Wald
age or for any person of any age who was not          chi-square test. Crude odds ratios (cORs) and
home; verbal informed assent was obtained             95% confidence intervals (CIs) were calcu-
for those aged 7 to 19 years (individuals less        lated; Fisher’s exact test was used to deter-
than 20 are considered minors in Thailand)            mine significance when expected cell size was
after permission from the caretaker was ob-           less than 5.
tained verbally. Approval from both the CDC
Institutional Review Board and the Thailand                                RESULTS
Ministry of Public Health Ethical Review Com-
                                                           During the time period beginning May 28,
mittee was obtained prior to beginning the sur-
                                                      2003 and ending June 20, 2003, we visited
vey.
                                                      1,600 households, of which 1,598 (99.9%) had
      Variables were dichotomized as follows:         a caretaker who agreed to participate. One
(1) age less than 18 years or age 18 years or         household was deemed a “no response”
more; (2) monthly household income 5,000              household and the caretaker of the other
baht or less (US$ 125) or more than 5,000             household declined to participate. A total
baht; and (3) caretaker education less than           study population of 5,658 persons was inter-
secondary school or at least secondary                viewed, giving a median 3 persons per house-
school. A case household was defined as a             hold with a range of 1 to 12 persons per
household with at least 1 case-patient. Very          household. Half of the study population was
severe pneumonia in a child less than 3 years         male and age ranged from less than 1 year to
of age was defined using the Integrated Man-          108 years (Table 1). Seventy-one percent
agement of Childhood Illnesses guidelines             (1,131/1,597) of households had a monthly
(WHO, 2000), – cough or difficulty breathing          income of 5,000 baht or less (US$ 125); 86%
plus at least 1 of the following: central cyano-      (1,382/1,598) had a primary caretaker with
sis, poor feeding, seizures, unconsciousness,         less than a secondary school education; 94%
or decreased activity. Severe illness in a per-       (1,507/1,598) had a television, radio, or tele-
son 3 years of age or more was defined as             phone; and 48% (772/1,598) of households
difficulty breathing, fast breathing, and confu-      had a primary source of income from farming/
sion during the illness.                              agriculture.
     SAS 8.2 (SAS Institute, Cary, NC) was                Of the 5,658 persons interviewed, 62
used to perform descriptive analysis. We re-          (1%, 95% CI: 0.8-1.4) met the pneumonia
port frequencies with Fleiss quadratic 95%            case definition, yielding a rate of 11 cases per
confidence intervals. Because a self-weight-          1,000 persons (95% CI: 8.6-14.1 cases per


552                                                                          Vol 39 No. 3 May 2008
                                        PNEUMONIA S URVEILLANCE   IN   THAILAND


                  Table 1                                   three years of age or older met the criteria for
 Demographic characteristics of the study                   severe illness. Fifty-four (92%, 95% CI: 81-97)
 population (N=5,658) and case-patients                     sought care for their illness, but 1 of these
  (n=62) in a household survey examining                    individuals sought care outside of Sa Kaeo
health-seeking patterns for pneumonia, Sa                   Province, leaving 53 (90%, 95% CI: 79-96) of
    Kaeo Province, Thailand, June 2003.                     the 59 patients having sought care in Sa Kaeo
                                                            Province. The following were reasons (not
Characteristic                Total          Case-          mutually exclusive) why the 5 individuals did
                           population       patients        not seek care: (1) not sick enough (n=3); (2)
                             (%)              (%)
                                                            thought getting better (n=2); (3) thought would
Age group (yrs)                                             get a serious disease (n=1); or (4) afraid of
  <3                         216   (3.8)    12   (19.4)     receiving an injection (n=1). All 5 of these in-
  3-17                     1,655   (29.3)   26   (41.9)     dividuals were males and all but one, who was
  18-64                    3,291   (58.2)   16   (25.8)     9 years old, was over 50 years of age.
  ≥65                        448   (7.9)     8   (12.9)
                                                                  Of the 59 case-patients, 47 (80%, 95%
  Missing                     48   (0.8)     -
                                                            CI: 67-89) sought care at the level of a hospi-
Less than five years of age 408    (7.2)    21   (33.9)
                                                            tal (outpatient, emergency, or inpatient depart-
Male                       2,800   (49.5)   41   (66.1)
Female                     2,854   (50.4)   21   (33.9)     ment) within the province. Individuals who
Missing                        4   (-)       -              were younger appeared to be more likely to
                                                            go to a hospital when seeking care than indi-
                                                            viduals who were older: 0-14 years of age [32/
                                                            37 (86%, 95% CI: 70-95)], 15-64 years of age
1,000 persons). The cases were distributed                  [10/14 (71%, 95% CI: 42-90)], and 65 years
among 26 of the 40 selected villages and there              and older [5/8 (63%, 95% CI: 26-90)]. Nine-
were 3 households with 2 cases each. The                    teen individuals received a chest radiograph
majority [60/62 (96.8%)] met the case defini-               and 11 were hospitalized; 8 of these individu-
tion by having cough and difficulty breathing               als received both. The rate of hospitalized
for at least 2 days alone or in combination with            pneumonia in this study population was 2
being given a diagnosis of pneumonia by a                   cases per 1,000 persons. Almost all individu-
health-care provider; 2 case-patients met the               als [56/59 (95%, 95% CI: 85-99)] reported
case definition by being given a diagnosis of               having taken some medication for the illness,
pneumonia only. Three case-patients did not                 45 (80%, 95% CI: 67-89) of whom stated it
have the more detailed questionnaire admin-                 was an antibiotic but could not provide the
istered. In the remainder of the results, we                name.
describe the 59 cases for which we have com-                     The most frequently visited sites for medi-
plete information. Nine individuals answered                cal care were the outpatient departments, pri-
the detailed questionnaire themselves; the                  vate physician clinics, and health centers; this
caretaker served as a proxy for the remaining               pattern was similar to that for where care was
50 case-patients.                                           sought first (Table 2). Overall, 72% (38/53,
     Case-patients had duration of illness                  95% CI: 57-83) of case-patients who sought
ranging from 1 to 40 days with a median of 7                care visited 2 or more places, although all
days. Eleven (92%, 95% CI: 60-100) of the                   case-patients who first sought care at a health
12 children less than 3 years of age met the                center subsequently sought care elsewhere.
IMCI criteria for very severe pneumonia and                 Among the 11 case-patients who were admit-
12 (26%, 95% CI:14-41) of the 47 individuals                ted to the hospital, 8 (73%, 95% CI: 39-93)


Vol 39 No. 3 May 2008                                                                                   553
                                  SOUTHEAST ASIAN J TROP MED PUBLIC H EALTH


                  Table 2                                  mates calculated from the active surveillance
  Pattern of health-seeking among case-                    system may be underestimating the true inci-
   patients who sought care (n=53) in a                    dence of pneumonia by as much as 20%.
   household survey examining health-
 seeking patterns for pneumonia, Sa Kaeo                                    DISCUSSION
      Province, Thailand, June 2003.
                                                                Our study found that the majority of indi-
 Location                     No.       No. who went
                                                           viduals with self-reported pneumonia sought
                              (%)a       there first (%)
                                                           care at the level of the hospital at some point
                                                           during the course of their illness. Because one
 Outpatient departmentb     36 (67.9)      19 (35.8)
 Private physician clinic   29 (54.7)      14 (26.4)
                                                           of the required criteria of this hospital-based
 Health center              18 (34.0)      12 (22.6)       surveillance system is reaching the hospital
 Inpatient departmentb      11 (20.8)       1 (1.9)        where an individual has the opportunity to have
 Drug seller                 4 (7.5)        3 (5.7)        a chest radiograph and/or be admitted to the
 Emergency departmentb       2 (3.8)        2 (3.8)        hospital, our study findings suggest that most
 Pharmacy                    1 (1.9)        1 (1.9)        pneumonia cases could be captured by this
 Health volunteer            1 (1.9)        1 (1.9)        active, population-based surveillance system,
aSum
                                                           provided chest radiographs are readily avail-
     is greater than 53 because some case-patients
                                                           able and utilized. Further examination of who
 sought care from more than one place
bConsidered a hospital facility                            gets a chest radiograph among individuals
                                                           with possible pneumonia is addressed else-
                                                           where (Olsen et al, 2006).
sought care at a private physician’s office im-                  Travel time and cost were originally hy-
mediately prior to being admitted to the hos-              pothesized as potential barriers to care given
pital. For 1 person, the hospital inpatient                the rural nature of the province and the low
department was the first and only place he                 average household income. However, this was
sought care. The other 2 individuals sought                not the case based on self-reported informa-
care at an outpatient department or from a                 tion from this study. Instead, self-assessments
drug seller prior to hospital admission.                   that the illness was not severe enough or was
      The survey and the surveillance system               improving and fear of going to the doctor were
overlapped for 5 months (September 2002 -                  reasons for not seeking healthcare services.
January 2003). During this time, 5 of the 11                    The extended period of illness recall, up
case-patients reportedly were admitted to a                to 18 months prior to the interview, may have
hospital in Sa Kaeo. To try and assess valid-              led to selective reporting of more severe ill-
ity, data (name, age, sex, month of onset) on              nesses. Although shorter recall times are as-
4 of 5 patients were known and could be com-               sociated with more accurate reporting of in-
pared to surveillance records. Only one was                formation, the seasonal nature and low re-
considered a match. However, nicknames                     ported baseline incidence of pneumonia pre-
were reported on the survey forms instead of               vented us from shortening the recall time. In
full names, making the comparisons difficult.              addition, the use of self-reporting and proxies
     In this study, 12 (20%, 95% CI: 11-33) of             during the interviews could have introduced
the 59 case-patients did not seek care at the              additional biases.
level of a hospital within the province. If we                 Misclassification was also a concern, as the
assume that the 12 individuals who did not                 case definition was moderately sensitive and
seek care truly had pneumonia, then the esti-              specific. Given that our rate of hospitalized pneu-


554                                                                                Vol 39 No. 3 May 2008
                                        PNEUMONIA S URVEILLANCE   IN   THAILAND


monia was equivalent to that found in the pas-                         infants and young children. Recommendations
sive surveillance system (Kanlayanaphotporn                            of the Advisory Committee on Immunization
et al, 2004), we surmise that our definition                           Practices (ACIP). MMWR 2000; 49(RR-9): 1-
was only moderately sensitive. However, with                           35.
different case definitions it is difficult to directly      Chen L, Huq E, D’Souza S. Sex bias in the family allo-
compare the two rates. On the other hand, it                    cation of food and health care in Bangladesh.
is possible that self-reported cases of pneu-                   Popul Dev Rev 1981; 7: 55-70.
monia in our study may not actually have been               D’Souza RM. Role of health-seeking behaviour in
pneumonia but a more mild acute respiratory                     child mortality in the slums of Karachi, Paki-
infection given the moderate level of specific-                 stan. J Biosoc Sci 2003; 35: 131-44.
ity in the case definition. However, since we               Das Gupta M. Selective discrimination against fe-
were most concerned about people’s ability                      male children in rural Punjab, India. Popul Dev
to travel to the hospital and our study group                   Rev 1987; 13: 77-100.
potentially included individuals with more mild             Forgie IM, O’Neill KP, Lloyd-Evans N, et al. Etiology
illness, we can presume that people will be                      of acute lower respiratory tract infections in
just as likely, if not more, to seek care when                   Gambian children: I. Acute lower respiratory
more severely ill with pneumonia. A second-                      tract infections in infants presenting at the
ary problem with our case definition was that                    hospital. Pediatr Infect Dis J 1991a; 10: 33-41.
we used the same case definition for adults                 Forgie IM, O’Neill KP, Lloyd-Evans N, et al. Etiology
given the lack of a consistent case definition                   of acute lower respiratory tract infections in
for pneumonia for adults.                                        Gambian children: II. Acute lower respiratory
                                                                 tract infection in children ages one to nine
     Thailand is a middle-income country with
                                                                 years presenting at the hospital. Pediatr Infect
good access to health care. In countries where                   Dis J 1991b; 10: 42-7.
similar surveillance systems are being estab-
                                                            Ganatra B, Hirve S. Male bias in health care utiliza-
lished, this approach to evaluating the cover-
                                                                tion for under-fives in a rural community in
age of the system should be considered, as
                                                                western India. Bull World Health Organ 1994;
hospital accessibility will vary between and                    72: 101-4.
within countries.
                                                            Ghafoor A, Nomani NK, Ishaq Z, et al. Diagnoses of
                                                                acute lower respiratory tract infections in chil-
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