Abstract              Background: Pandemic influenza A (H1N1) 2009 is a novel strain of influenza A virus evolved by genetic reassortment. The Influenza A H1N1 in humans can be a mild illness or in some people it may result in serious, even life-threatening complications such as pneumonia, acute bronchitis, worsening of chronic conditions, respiratory failure and death. Aims and objectives: To study the outcome and various factors associated with Outcomes in the swine flu patients reporting to the Tertiary health care centre. Materials and Methods: In the present retrospective descriptive, record-based study all the cases of suspected Influenza-like illness attending the study institute during the study period were selected and were investigated further. The diagnosis of h1n1 influenza A (swine flu) was confirmed by RT-PCR or culture. A predesigned semi-structured Performa was used to collect details such as socio-demographic details, detailed address, clinical data of patient (sign and symptoms, co- morbid condition), diagnostic findings of influenza testing, treatment history (use of ventilator), drug details (oseltamivir received or not), outcome details and details of current pregnancy if pregnant. The collected data was entered in Microsoft excel and was analysed and presented with appropriate tables and digraphs. Results: 87.04% patients were discharged after treatment whereas 12.96% was the mortality due to swine flu. Diabetes mellitus (16.67%) was the most common co-existing medical condition, followed by chronic renal failure (3.70%) and pregnancy (3.70%). Bilateral pneumonia was diagnosed on x-ray in 46.30% patients whereas unilateral consolidation was diagnosed in 11.11% patients. 14.81% patients required ventilator support. There was no statistically significant between age and outcome of h1n1 influenza A (swine flu). The proportion of female (55.56%) was more. Majority of the patients were form urban area and mortality was also higher in urban area. Among the patients with pneumonia 71.43% patients died as compared to the survived patients (59.57%) but the difference was not statistically significant. Out of the total 8 cases which required ventilatory support 7 died and the difference observed among survived and died was statistically significant. Conclusion: Thus we conclude that the case fatality rate of swine flu was 12.96%. Patients with pneumonia, diabetes mellitus, urban residence and requirement of ventilatory support were the associated factors with bad outcome.

Key Words: Swine flu, outcome, factors associated.

 

INTRODUCTION

Pandemic influenza A (H1N1) 2009 is a novel strain of influenza A virus evolved by genetic reassortment. This virus was first reported in Mexico in April 2009¹ and rapidly spread to various countries worldwide^1,2. Moreover, disease severity varies from mild illness in one country to much higher morbidity and mortality in another. In addition, virulence of the virus changed over time as the pandemic goes through subsequent waves of national and international spread.³The specific risk factors for acquiring swine flu infection, incidence rate and fatality of the epidemic could be unique to each community.⁴ An understanding of these factors in the community and the behaviour of community is essential for planning strategies for prevention and control. This scatters droplets contaminated with the Influenza A H1N1 virus into the air where it can be breathed by others.⁵ People with Influenza A H1N1 typically have a fever or high temperature and may also have aching muscles, decreased thirst, decreased appetite, rapid breathing, sore throat or dry cough. These symptoms are very similar to seasonal flu.⁶ The Influenza A H1N1 in humans can be a mild illness or in some people it may result in serious, even life-threatening complications such as pneumonia, acute bronchitis, worsening of chronic conditions, respiratory failure and death. People who are increased at risk for developing serious complications of the Influenza A H1N1 included are person under long term therapy, hospitalized patients, and pregnant women.

 

MATERIALS AND METHOD

The present retrospective record based cross sectional study was conducted at the Dr. Ulhas Patil Medical College and HospitalAll the cases of suspected Influenza-like illness attending the study institute during January 2015 to December 2015 were selected and were investigated further. Following case definitions were used to select the study patients.

Influenza-like illness (ILI): Fever (temperature of 100°F [37.8°C] or greater) with cough or sore throat in the absence of a known cause other than influenza^1,7,8.

A confirmed case of h1n1 influenza A (swine flu): An individual with an influenza-like illness with a laboratory-confirmed H1N1 influenza A virus detected by RT-PCR or culture ^1,7,8. Throat or nasal swab samples of suspected cases with influenza-like illness (ILI) were collected in Viral Transport Medium and sent to laboratories maintaining cold-chain. RNA was extracted by QIAamp Viral RNA Mini Kit (Qiagen, Germany). RNA of each isolate was tested by separate primer/probe sets for InfA, Universal Swine (swFluA), Swine H1 (swH1) and RNaseP (Applied Biosystems, USA) as per the CDC real-time RT-PCR protocol (ABI Step One Plus RT-PCR instrument – Applied Biosystems, USA)⁹. A predesigned semi-structured Performa was used to collect details such as socio-demographic details, detailed address, clinical data of patient (sign and symptoms, co- morbid condition), diagnostic findings of influenza testing, treatment history (use of ventilator), drug details (oseltamivir received or not), outcome details and details of current pregnancy if pregnant. The collected data was entered in Microsoft excel and was analysed and presented with appropriate tables and digraphs.

 

 

 

RESULTS

 

Table 1: Distribution according to outcome

It was seen that 87.04% patients were discharged after treatment whereas 12.96% was the mortality due to swine flu.

 

Table 2: Distribution according to associated factors

Diabetes mellitus (16.67%) was the most common co-existing medical condition, followed by chronic renal failure (3.70%) and pregnancy (3.70%). Other co-morbidities include stroke, seizure and malignancy. Bilateral pneumonia was diagnosed on x-ray in 46.30% patients whereas unilateral consolidation was diagnosed in 11.11% patients. Bilateral hilar enlargement was seen in 3.70%. Normal x-ray was observed in 38.89% patients. It was observed that 14.81% patients required ventilator support.

 

Table 3: Association between various risk factors and outcome

It was observed that there was no statistically significant between age and outcome of h1n1 influenza A (swine flu). It was observed the proportion of female (55.56%) was more as compared to male (44.63%). It was observed that majority of the patients were form urban area and mortality was also higher in urban area. Among the patients with pneumonia 71.43% patients died as compared to the survived patients (59.57%) but the difference was not statistically significant. Out of the total 8 cases which required ventilatory support 7 died and the difference observed among survived and died was statistically significant.

DISCUSSION

The present study was conducted with the aim to study the outcome and various factors associated with the swine flu patients. It was seen that 87.04% patients were discharged after treatment whereas 12.96% was the mortality due to swine flu. Chaudhari AI et al¹⁰ reported mortality of 17% in their study. Case fatality rate between 20 to 25 % was observed in other studies carried out in Ahmedabad, Maharashtra, and Surat.^11,12,13 Diabetes mellitus (16.67%) was the most common co-existing medical condition, followed by chronic renal failure (3.70%) and pregnancy (3.70%). Other co-morbidities include stroke, seizure and malignancy. Almost similar result were observed in study carried out by H Rana et al⁴, Ketan K Patel et al,¹⁴ Chaudhari AI et al¹⁰ and Asmita A. Mehta et al¹⁵ Bilateral pneumonia was diagnosed on x-ray in 46.30% patients whereas unilateral consolidation was diagnosed in 11.11% patients. Bilateral hilar enlargement was seen in 3.70%. Normal x-ray was observed in 38.89% patients. Similar findings were also observed by Asmita A. Mehta et al¹⁵. Bilateral patchy infiltrates at time of admission, was another risk factor associated with need of mechanical ventilation or mortality which was diagnosed on x-ray. Bilateral pneumonia on chest X-ray might be due to bacterial pneumonia, acute respiratory distress syndrome or progressive viral pneumonia. It was observed that 14.81% patients required ventilator support. Similar result were observed in study carried out by Chaudhari AI et al¹⁰ and Asmita A. Mehta et al¹⁵. It was observed that there was no statistically significant between age and outcome of h1n1 influenza A (swine flu). It was observed the proportion of female (55.56%) was more as compared to male (44.63%). It was observed that majority of the patients were form urban area and mortality was also higher in urban area. Malhotra et al¹⁶ reported that mortality was higher (63.5%) in urban areas, especially in women. The findings were comparable findings reported by Chaudhari AI et al¹⁰ and Asmita A. Mehta et al¹⁵ in their studies. Among the patients with pneumonia 71.43% patients died as compared to the survived patients (59.57%) but the difference was not statistically significant. The most common cause of death was hypoxaemic respiratory failure with or without acute respiratory distress syndrome whereas in some cases it was multi organ dysfunction syndrome. Out of the total 8 cases which required ventilatory support 7 died and the difference observed among survived and died was statistically significant. Similar findings were also reported by Chaudhari AI et al¹⁰ and Asmita A. Mehta et al¹⁵ in their studies. This was a retrospective study that included only hospitalized patients of a tertiary care institute, probably reflecting the tip of the iceberg as the milder forms would have been missed at the community level. Most of the cases caused by the influenza A (H1N1) virus have been mild and self-limiting in nature, with higher risk of adverse outcome among certain risk groups.¹⁷ Early therapy with Oseltamivir has been found to reduce the duration of hospitalisation and the risk of progression to severe disease requiring admission to intensive care unit or resulting in death.^18,19 According to the Government of India's guidelines for categorisation of influenza A H1N1 cases for home isolation, testing, treatment and hospitalisation, patients with milder symptoms should be isolated at home (category A); patients with influenza-like illness with known risk factors or high-grade fever are treated with Oseltamivir with home isolation (category B); whereas patients with severe symptoms such as breathlessness, chest pain, drowsiness, fall in blood pressure, sputum mixed with blood, bluish discolouration of nails, etc., should be hospitalised and treated with Oseltamivir (category C).²⁰

 

CONCLUSION

Thus we conclude that the case fatality rate of swine flu was 12.96%. Patients with pneumonia, diabetes mellitus, urban residence and requirement of ventilatory support were the associated factors with bad outcome.

 

REFERENCES

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