Establishment of reference intervals during normal pregnancy through six months postpartum in western Kenya

PLoS ONE, Volume 12, No. 4, Year 2017

Interprétation

Background Pregnancy is associated with changes in hematological and biochemistry values, yet there are no African reference intervals for clinical management of pregnant women. We sought to 1) develop laboratory reference intervals during pregnancy and up to 24 weeks postpartum and 2) determine the proportion of women in a previous clinical trial who would be misclassified as having out-of-range values using reference intervals from a United States (U. S.) population. Methods and findings This was a longitudinal sub-study of 120 clinically healthy, HIV-uninfected, self-selected pregnant women seeking antenatal care services at either of two public hospitals in western Kenya. Blood specimens were obtained from consented women at gestational ages 28 and36 weeks and at 2, 6, 14 and 24 weeks postpartum. Median and 95% reference intervals were calculated for immune-hematological and biochemistry parameters and compared to reference intervals from a Kenyan and United States (U.S.) population, using Wilcoxon tests. Differences with p<0.05 were considered significant. Some hematological parameters, including hemoglobin and neutrophils showed significant variations compared to reference intervals for non-pregnant women. Hemoglobin values were significantly lower during pregnancy but were comparable to the values in non-pregnant women by 6 weeks postpartum. CD4, CD8 and platelets were significantly elevated in early postpartum but declined gradually, reaching normal levels by 24 weeks postpartum. Using the new hemoglobin reference levels from this study to estimate prevalence of 'out of range' values in a prior Kisumu research cohort of pregnant/postpartum women, resulted in 0% out of range values, in contrast to 96.3% using US non-pregnant reference values Conclusion There were substantial differences in U.S. and Kenyan values for immune-hematological parameters among pregnant/postpartum women, specifically in red blood cell parameters in late pregnancy and 2 weeks postpartum. Use of U.S. reference intervals markedly increases likelihood of out of range values, highlighting the need for suitable locally developed reference intervals. Participants included in our analyses were recruited from a longitudinal cohort study, the Mama Salama study, the aims of which were to define the incidence of HIV infection and identify risk factors associated with HIV infection during peri/postpartum period. Study participants comprised pregnant women seeking antenatal care services at two public hospitals in the former Nyanza Province of Kenya, Bondo County hospital and Ahero sub-County hospital from May 2011 to July 2014. Women were eligible to participate if they were HIV uninfected (based on rapid HIV testing and nucleic acid amplification test [NAAT] at enrolment and subsequently negative on NAAT throughout the study), pregnant, with a plan to remain in the area until at least 9 months postpartum, willing to have serial visits at maternal child health clinic with serial HIV testing through 9 months postpartum, not on medication that could alter hematological parameters, and no clinical evidence of malaria and helminth infections. Blood specimens for hematological and biochemistry values were obtained from consented women 14 years and above at 28 and 36 weeks gestation as well as at 2, 6, 14 and 24 weeks postpartum. The study and the consenting procedures were approved by the Kenya Medical Research Institute’s (KEMRI) ethics review committee, University of Nairobi/Kenyatta National Hospital Ethics and Research Committee (ERC) and University of Washington Institutional Review Board (IRB). Written informed consent was obtained from participants prior to any study procedure. All specimens had a unique study identification linked to the main study consent. For all critical values, participants were referred for clinical management per Kenya standard of care. Whole blood was collected in ethylenediaminetetraacetic acid vacutainer tubes (Becton Dickinson, Franklin Lakes, NJ) and transported at 4°C to the KEMRI HIV-research laboratory within six hours of specimen collection for processing and analysis. Initially, HIV status was determined using HIV rapid test kits as follows: Determine (Abbot Laboratories, Tokyo, Japan), and Bioline (Standard Diagnostics Inc., Korea) as a confirmatory test for any positive specimen and Unigold (Trinity Biotech Plc, Bray, Ireland), as a tie breaker. Later, HIV infection at enrolment was determined using the new Kenyan testing algorithm, with KHB (Shangai, Kehua Bioengineering Co. Ltd) as primary kit and First Response (PMC Medical Pty. Ltd) as the confirmatory kit. Unigold was used as the tie breaker for any specimen with an indeterminate result. Absolute WBC counts and percentages for leukocytes with differentials (neutrophils, lymphocytes, monocytes, eosinophils, and basophils), RBC with parameters Hb, Hct and mean cell volume (MCV), and platelet counts were determined from whole blood using a Coulter ACT 5Diff CP analyzer (Beckman Coulter, France). This was performed within 24 hours of specimen collection as recommended by the manufacturer (www.beckmancoulter.com). Clinical chemistries were analyzed from serum obtained from serum separation tubes (Becton Dickinson, Franklin Lakes, NJ). Specimens were analyzed for ALT, aspartate aminotransferase (AST), bilirubin (Bil) and creatinine (Cr) using the Cobas Integra 400 plus biochemistry analyzer (Roche, Germany) per the manufacturer’s instructions (www.usdiagnostics.roche.com). Quality control protocols included running known standards each day before testing specimens. In addition, the laboratory is enrolled in external quality assurance testing programs with the College of American Pathologists (CAP) (hematology, and clinical chemistry) and the United Kingdom National External Quality Assurance Service (UK NEQAS) (lymphocyte immunophenotyping and hematology). The laboratory has satisfactory performance in UK NEQAS (Lymphocyte Immunophenotyping) and CAP Clinical Chemistry as well as CAP Hematology over the past three years. Based on the CLSI guidelines recommendation of 120 reference subjects for establishing reference intervals and assuming a loss to follow up rate of 20%, 150 pregnant women were targeted for enrollment. Every 6th woman in the parent study was targeted for enrollment into the reference interval sub-study. All data available at each time point were entered into an Access database and the median and 95% reference intervals (2.5 and 97.5 percentiles) for immune-hematological and biochemistry parameters calculated using SAS (SAS system for Windows 9.2; SAS, Inc., Cary, NC). These values were compared to established reference intervals developed for non-pregnant women in western Kenya [16], using the Wilcoxon test. Differences with p≤0.05 were considered significant. In order to demonstrate the use of appropriate reference intervals for a given population, we determined how many of 522 participants in a previous clinical trial, KiBS [17], would have out-of-range values using the newly established reference intervals in the current study, the intervals for non-pregnant women in western Kenya and the intervals from a U.S. population of non-pregnant women [18]. Additionally, we determined the number of women who would have abnormal values using the 2004 National Institutes of Health Division of AIDS (DAIDS) toxicity tables [19].

Résumé de l’IA

Study Justification:

– Pregnancy is associated with changes in hematological and biochemistry values, but there are no African reference intervals for clinical management of pregnant women.
– This study aimed to develop laboratory reference intervals during pregnancy and up to 24 weeks postpartum.
– It also aimed to determine the proportion of women who would be misclassified using reference intervals from a United States population.

Study Highlights:

– The study included 120 clinically healthy, HIV-uninfected pregnant women in western Kenya.
– Blood specimens were obtained at different time points during pregnancy and postpartum.
– Reference intervals were calculated for immune-hematological and biochemistry parameters.
– Significant variations were found in certain parameters compared to reference intervals for non-pregnant women.
– Hemoglobin values were lower during pregnancy but returned to normal levels by 6 weeks postpartum.
– CD4, CD8, and platelet levels were elevated in early postpartum but gradually declined to normal levels by 24 weeks postpartum.
– Use of U.S. reference intervals increased the likelihood of out-of-range values compared to locally developed reference intervals.

Recommendations:

– Develop and implement locally developed reference intervals for immune-hematological and biochemistry parameters in pregnant and postpartum women in Kenya.
– Use these locally developed reference intervals for clinical management of pregnant and postpartum women.
– Disseminate the findings of this study to healthcare providers and policymakers to raise awareness about the need for suitable locally developed reference intervals.

Key Role Players:

– Researchers and scientists specializing in hematology, biochemistry, and obstetrics.
– Healthcare providers, including doctors, nurses, and midwives.
– Policy makers and government officials responsible for healthcare planning and resource allocation.

Cost Items for Planning Recommendations:

– Research and laboratory equipment for analyzing hematological and biochemistry parameters.
– Training and capacity building for healthcare providers on the use of locally developed reference intervals.
– Awareness campaigns and educational materials for healthcare providers and policymakers.
– Monitoring and evaluation of the implementation of locally developed reference intervals.
– Collaboration and coordination with relevant stakeholders, such as government health departments and international organizations.

Force de la preuve

The strength of evidence for this abstract is 8 out of 10.
The evidence in the abstract is strong, as it presents a well-designed longitudinal study with a clear objective and methodology. The study includes a sufficient number of participants and compares the reference intervals from a Kenyan population to those from a US population. The findings show significant differences in hematological and biochemistry parameters between the two populations. To improve the evidence, the abstract could provide more details on the statistical analysis used and the clinical implications of the findings.

Abstrait

Participants included in our analyses were recruited from a longitudinal cohort study, the Mama Salama study, the aims of which were to define the incidence of HIV infection and identify risk factors associated with HIV infection during peri/postpartum period. Study participants comprised pregnant women seeking antenatal care services at two public hospitals in the former Nyanza Province of Kenya, Bondo County hospital and Ahero sub-County hospital from May 2011 to July 2014. Women were eligible to participate if they were HIV uninfected (based on rapid HIV testing and nucleic acid amplification test [NAAT] at enrolment and subsequently negative on NAAT throughout the study), pregnant, with a plan to remain in the area until at least 9 months postpartum, willing to have serial visits at maternal child health clinic with serial HIV testing through 9 months postpartum, not on medication that could alter hematological parameters, and no clinical evidence of malaria and helminth infections. Blood specimens for hematological and biochemistry values were obtained from consented women 14 years and above at 28 and 36 weeks gestation as well as at 2, 6, 14 and 24 weeks postpartum. The study and the consenting procedures were approved by the Kenya Medical Research Institute’s (KEMRI) ethics review committee, University of Nairobi/Kenyatta National Hospital Ethics and Research Committee (ERC) and University of Washington Institutional Review Board (IRB). Written informed consent was obtained from participants prior to any study procedure. All specimens had a unique study identification linked to the main study consent. For all critical values, participants were referred for clinical management per Kenya standard of care. Whole blood was collected in ethylenediaminetetraacetic acid vacutainer tubes (Becton Dickinson, Franklin Lakes, NJ) and transported at 4°C to the KEMRI HIV-research laboratory within six hours of specimen collection for processing and analysis. Initially, HIV status was determined using HIV rapid test kits as follows: Determine (Abbot Laboratories, Tokyo, Japan), and Bioline (Standard Diagnostics Inc., Korea) as a confirmatory test for any positive specimen and Unigold (Trinity Biotech Plc, Bray, Ireland), as a tie breaker. Later, HIV infection at enrolment was determined using the new Kenyan testing algorithm, with KHB (Shangai, Kehua Bioengineering Co. Ltd) as primary kit and First Response (PMC Medical Pty. Ltd) as the confirmatory kit. Unigold was used as the tie breaker for any specimen with an indeterminate result. Absolute WBC counts and percentages for leukocytes with differentials (neutrophils, lymphocytes, monocytes, eosinophils, and basophils), RBC with parameters Hb, Hct and mean cell volume (MCV), and platelet counts were determined from whole blood using a Coulter ACT 5Diff CP analyzer (Beckman Coulter, France). This was performed within 24 hours of specimen collection as recommended by the manufacturer (www.beckmancoulter.com). Clinical chemistries were analyzed from serum obtained from serum separation tubes (Becton Dickinson, Franklin Lakes, NJ). Specimens were analyzed for ALT, aspartate aminotransferase (AST), bilirubin (Bil) and creatinine (Cr) using the Cobas Integra 400 plus biochemistry analyzer (Roche, Germany) per the manufacturer’s instructions (www.usdiagnostics.roche.com). Quality control protocols included running known standards each day before testing specimens. In addition, the laboratory is enrolled in external quality assurance testing programs with the College of American Pathologists (CAP) (hematology, and clinical chemistry) and the United Kingdom National External Quality Assurance Service (UK NEQAS) (lymphocyte immunophenotyping and hematology). The laboratory has satisfactory performance in UK NEQAS (Lymphocyte Immunophenotyping) and CAP Clinical Chemistry as well as CAP Hematology over the past three years. Based on the CLSI guidelines recommendation of 120 reference subjects for establishing reference intervals and assuming a loss to follow up rate of 20%, 150 pregnant women were targeted for enrollment. Every 6th woman in the parent study was targeted for enrollment into the reference interval sub-study. All data available at each time point were entered into an Access database and the median and 95% reference intervals (2.5 and 97.5 percentiles) for immune-hematological and biochemistry parameters calculated using SAS (SAS system for Windows 9.2; SAS, Inc., Cary, NC). These values were compared to established reference intervals developed for non-pregnant women in western Kenya [16], using the Wilcoxon test. Differences with p≤0.05 were considered significant. In order to demonstrate the use of appropriate reference intervals for a given population, we determined how many of 522 participants in a previous clinical trial, KiBS [17], would have out-of-range values using the newly established reference intervals in the current study, the intervals for non-pregnant women in western Kenya and the intervals from a U.S. population of non-pregnant women [18]. Additionally, we determined the number of women who would have abnormal values using the 2004 National Institutes of Health Division of AIDS (DAIDS) toxicity tables [19].

Matériaux

N/A

Innovations

One potential innovation to improve access to maternal health based on the provided information is the establishment of locally developed reference intervals for hematological and biochemistry values during pregnancy and postpartum. This innovation aims to address the lack of African reference intervals for clinical management of pregnant women, which can lead to misclassification of out-of-range values and inappropriate medical interventions.

By conducting a longitudinal sub-study involving clinically healthy pregnant women in western Kenya, reference intervals for immune-hematological and biochemistry parameters can be developed. These reference intervals can then be compared to reference intervals from a Kenyan population and reference intervals from a United States population.

The results of this study can help healthcare providers in Kenya accurately interpret laboratory test results for pregnant women, leading to improved clinical management and appropriate interventions. It can also reduce the reliance on reference intervals from other populations, which may not accurately reflect the physiological changes during pregnancy in the local context.

Overall, the establishment of locally developed reference intervals for maternal health parameters can contribute to improving access to quality maternal healthcare in Kenya and potentially in other African countries as well.

AI Innovations Description

The recommendation based on the study is to establish reference intervals for hematological and biochemistry values during pregnancy and up to 24 weeks postpartum in western Kenya. This is important because there are currently no African reference intervals for clinical management of pregnant women. By developing locally relevant reference intervals, healthcare providers can accurately assess and monitor the health of pregnant women, leading to improved access to maternal health services. The study found significant variations in immune-hematological parameters among pregnant and postpartum women in Kenya compared to reference intervals from the United States. Using the newly established reference intervals from this study resulted in a lower prevalence of out-of-range values compared to using US reference values. This highlights the need for suitable locally developed reference intervals to ensure accurate diagnosis and appropriate clinical management.

AI Innovations Methodology

Based on the provided information, here are some potential recommendations for improving access to maternal health:

1. Develop and implement locally derived reference intervals: Establishing reference intervals specific to the population in western Kenya can help healthcare providers accurately interpret laboratory results during pregnancy and postpartum. This will enable better clinical management and reduce the likelihood of misclassification.

2. Train healthcare providers on the use of local reference intervals: Conduct training programs for healthcare providers to ensure they are aware of the newly developed reference intervals and understand how to interpret and utilize them effectively in their practice.

3. Integrate reference intervals into electronic health records (EHR) systems: Incorporate the locally derived reference intervals into the EHR systems used in healthcare facilities. This will facilitate automatic interpretation of laboratory results and provide real-time feedback to healthcare providers, ensuring consistent and accurate management of maternal health.

4. Raise awareness among pregnant women: Conduct educational campaigns to inform pregnant women about the importance of regular antenatal care and the significance of laboratory tests. Emphasize the use of locally derived reference intervals to improve the accuracy of test results and subsequent clinical decisions.

To simulate the impact of these recommendations on improving access to maternal health, a methodology could be developed as follows:

1. Define the study population: Identify a representative sample of pregnant women in western Kenya who are seeking antenatal care services at public hospitals.

2. Collect baseline data: Gather information on the current practices and challenges related to access to maternal health, including the use of reference intervals and laboratory testing.

3. Implement the recommendations: Introduce the recommended interventions, such as developing locally derived reference intervals, training healthcare providers, integrating reference intervals into EHR systems, and conducting awareness campaigns for pregnant women.

4. Monitor and evaluate: Track the implementation of the recommendations and collect data on key indicators, such as the utilization of reference intervals, changes in laboratory result interpretation, and improvements in maternal health outcomes.

5. Analyze the data: Use statistical methods to analyze the collected data and assess the impact of the recommendations on improving access to maternal health. This could include comparing pre- and post-intervention data, evaluating changes in laboratory result interpretation, and measuring improvements in maternal health indicators.

6. Draw conclusions and make recommendations: Based on the analysis, draw conclusions about the effectiveness of the recommendations in improving access to maternal health. Identify any challenges or areas for further improvement and make recommendations for future interventions or modifications to the existing recommendations.

By following this methodology, it will be possible to simulate the impact of the recommendations on improving access to maternal health and provide evidence-based insights for further interventions and policy decisions.

Auteurs et co-auteurs

Statistics:

Citations: 5

Authors: 9

Identifiers:

DOI: 10.1371/journal.pone.0175546

Research Areas:

Health System and Policy, Infectious Diseases, Maternal Access, Maternal and Child Health, Quality of Care, Sexual and Reproductive Health

Study Countries:

Kenya

Study Design:

Cohort Study, Cross Sectional Study

Study Approach:

Quantitative

Participants Gender:

Female

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