Diabetes mellitus, hypertension and albuminuria in rural Zambia: a hospital-based survey

Authors

  • Jon B. Rasmussen,

    Corresponding author
    1. Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
    • Corresponding Author Jon B. Rasmussen, University of Copenhagen Øster Farimagsgade 5, P.O.B. 2099, DK-1014 Copenhagen K, Denmark. Tel.: +45 3532 7626; Fax: +45 3532 7736; E-mail: jbr@outlook.dk

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  • Jakúp A. Thomsen,

    1. Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
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  • Peter Rossing,

    1. Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
    2. Steno Diabetes Center, Gentofte, Denmark
    3. Faculty of Health, Aarhus University, Aarhus, Denmark
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  • Shelagh Parkinson,

    1. Dr. Gray's Hospital, Elgin, UK
    2. St. Francis' Hospital, Katéte, Zambia
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  • Dirk L. Christensen,

    1. Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
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  • Ib C. Bygbjerg

    1. Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
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Abstract

Objective

To assess albuminuria in rural Zambia among patients with diabetes mellitus only (DM group), hypertension only (HTN group) and patients with combined DM and HTN (DM/HTN group).

Methods

A cross-sectional survey was conducted at St. Francis Hospital in the Eastern province of Zambia. Albumin–creatinine ratio in one urine sample was used to assess albuminuria. Other information obtained included age, sex, body mass index (BMI), waist circumference (WC), blood pressure (BP), glycosylated haemoglobin (HbA1c), random capillary glucose, time since diagnosis, medication and family history of DM or HTN.

Results

A total of 193 participants were included (DM group: = 33; HTN group: n = 92; DM/HTN group: n = 68). The participants in the DM group used insulin more frequently as diabetes medication than the DM/HTN group (P < 0.05). Furthermore, the DM group was younger and had lower BMI, WC and BP than the two other groups. In the DM group, HTN group and DM/HTN group, microalbuminuria was found in 12.1%, 19.6% and 29.4% (= 0.11), and macroalbuminuria was found in 0.0%, 3.3% and 13.2% (P = 0.014), respectively. The urine albumin (P = 0.014) and albumin–creatinine ratio (P = 0.0006) differed between the three groups.

Conclusion

This hospital-based survey in rural Zambia found a lower frequency of albuminuria among the participants than in previous studies of patients with DM or HTN in urban sub-Saharan Africa.

Abstract

Objectif

Evaluer l'albuminurie en zone rurale en Zambie chez les patients atteints du diabète sucré seul (groupe DM), d'hypertension seule (groupe HTN) et chez ceux souffrant des deux (groupe DM/HTN).

Méthodes

Une enquête transversale a été menée à l'Hôpital Saint-François, dans la province orientale de la Zambie. Le rapport albumine/créatinine sur un échantillon d'urine a été utilisé pour évaluer l'albuminurie. D'autres informations obtenues comprenaient: l’âge, le sexe, l'indice de masse corporelle, le tour de taille, la pression artérielle, l'hémoglobine glycosylée (HbA1c), le glucose capillaire aléatoire, le temps écoulé depuis le diagnostic, les médicaments et les antécédents familiaux de DM ou d’HTN.

Résultats

193 sujets ont été inclus (groupe DM: n = 33, groupe HTN: n = 92 et groupe DM/HTN: n = 68). Les participants du groupe DM ont utilisé de l'insuline plus souvent comme médicament contre le diabète que ceux du groupe DM/HTN (P < 0,05). De plus, le groupe DM était plus jeune, avait un indice de masse corporelle, un tour de taille et une pression artérielle inférieurs à ceux des deux autres groupes. La microalbuminurie détectée chez le groupe DM, le groupe HTN et le groupe DM/HTN était de 12,1%, 19,6% et 29,4% (P = 0,11) respectivement et la macroalbuminurie: 0,0%, 3,3% et 13,2% (P = 0,014), respectivement. L'albumine urinaire (P = 0,014) et le rapport albumine/créatinine (P = 0,0006) différaient entre les trois groupes.

Conclusion

Cette étude en milieu hospitalier rural en Zambie a trouvé une fréquence d'albuminurie chez les participants inférieure à celle rapportée par des études précédentes sur des patients atteints de DM ou d’HTN dans les zones urbaines en Afrique subsaharienne.

Abstract

Objetivo

Evaluar la albuminuria en zonas rurales de Zambia entre pacientes con solo diabetes mellitus (grupo DM), solo hipertensión (grupo HTN) y pacientes con una combinación de DM e HTN (grupo DM/HTN).

Métodos

Estudio croseccional realizado en el Hospital de St. Francis en la Provincia del Este, Zambia. El cociente albúmina-creatinina en una muestra de orina se utilizó para evaluar la albuminuria. Otra información obtenida incluía la edad, el sexo, el índice de masa corporal, la circunferencia de la cintura, la presión sanguínea, hemoglobina glucosilada (HbA1c), glucemia capilar aleatoria, tiempo desde el diagnóstico, medicación e historia familiar de DM o HTN.

Resultados

Se incluyeron 193 participantes (grupo DM: n = 33; grupo HTN: n = 92; grupo DM/HTN: n = 68). Los participantes en el grupo DM utilizaban la insulina más frecuentemente como medicación para la diabetes que el grupo DM/HTN (P < 0.05). Más aún, en el grupo DM eran más jóvenes, tenían un menor índice de masa corporal, una menor circunferencia de la cintura y una menor presión arterial que en los otros dos grupos. La microalbuminuria era de 12.1%, 19.6%, 29.4% (P = 0.11) y la macroalbuminuria era de 0.0%, 3.3% and 13.2% (P = 0.014) en el grupo DM, el grupo HTN y el grupo DM/HTN respectivamente. La albúmina en orina (P = 0.014) y el cociente albúmina-creatinina (P = 0.0006) diferían entre los tres grupos.

Conclusión

En este estudio hospitalario en Zambia rural se encontró una menor frecuencia de albuminuria entre participantes que en estudios previos de pacientes con DM o HTN en zonas urbanas de África subsahariana.

Introduction

Albuminuria (micro- and macroalbuminuria) has been extensively studied among patients with diabetes mellitus (DM) or hypertension (HTN) in the Western world and is known as a strong predictor of cardiovascular disease, end-stage renal disease (ESRD) and even early mortality(Mogensen 1984; Viazzi et al. 2010; Fox et al. 2012). Information on albuminuria among patients with DM or HTN in sub-Saharan Africa (SSA) is scarce. Previous studies have presented varying results and were conducted in urban areas (Lutale et al. 2007; Busari et al. 2011; Osafo et al. 2011; Danquah et al. 2012); studies from rural areas are virtually non-existent. DM and HTN are both major risk factors for albuminuria, and two-thirds of patients with DM in SSA have HTN (Choukem et al. 2007). The objective of this study was to assess albuminuria in rural Zambia among patients with DM or HTN by a more horizontal approach, that is, patients with DM only (DM group), patients with HTN only (HTN group) and patients with combined DM and HTN (DM/HTN group).

Materials and methods

Design, setting and ethics

A cross-sectional study was conducted at St. Francis Hospital, near Katéte in the Eastern province of Zambia from February to April 2011. St. Francis Hospital is a rural hospital with 300 beds, serving a population of approximately 200 000 and provides free medication and treatment for all who attend the hospital. All patients who had previously been diagnosed with DM or HTN and attended St. Francis Hospital outpatient department for a clinical review during the study period were invited to participate. The inclusion of participants was preceded by oral and written informed consent. DM was defined as HbA1c (≥6.5%) and/or ongoing treatment with diabetes medication and HTN as blood pressure (BP) ≥140/90 mmHg and/or ongoing treatment with antihypertensive medication. Exclusion criteria were a positive urine test for blood, nitrites or leucocytes or fever (defined as ear temperature ≥37.5 °C). All included patients were evaluated during one clinical review only. The study protocol was approved by the Ethics Committee of St. Francis Hospital and consultatively approved by the Developing Country sub-Committee of the National Committee on Biomedical Research Ethics in Denmark.

Procedures

Blood pressure was measured with the participant seated in a resting position for at least 10 min using the Omron M8 Comfort automatic BP monitor (Omron Corporation, Kyoto, Japan). Glycosylated haemoglobin (HbA1c) and urine albumin–creatinine ratio (ACR) in one urine sample were both measured with the Afinion AS100 Analyzer (Axis Shield PoC, Oslo, Norway). Cut-off values for microalbuminuria were ACR = 3.5–35.0 and ACR = 2.5–25.0 mg/mmol for women and men, respectively. Cut-off values for macroalbuminuria were ACR >35.0 and >25.0 for women and men, respectively. Weight, height, waist circumference (WC) and random capillary glucose were also measured. Information including age, smoking, medication, time since diagnosis, previously diagnosed comorbidity and family history of DM or HTN was obtained in an interview conducted in English or with an interpreter in the local language, Chichewa.

Statistical analyses

All values are given as medians and interquartile ranges unless otherwise specified. Categorical variables were compared by chi-square test or Fisher's exact test as appropriate. Continuous variables were compared by Kruskal–Wallis test. A P-value < 0.05 was considered statistically significant. Data were analysed using SAS 9.2 (SAS Institute inc., Cary, NC, USA).

Results

We invited 212 patients to participate; three refused, and seven were excluded because of repeated positive urine tests of blood, nitrites or leucocytes despite relevant treatment. Nine patients were excluded from the statistical analyses due to unavailable data. For all included participants (n = 193), age was 58 (50–68) years, 37.3% (72/193) of the participants were men, and 50.2% (97/193) had undetermined HIV status as they had never previously been HIV tested and refused to be tested in this study. Nine patients came for a review of their HTN only, but were diagnosed with DM at the inclusion procedures and thus placed in the DM/HTN group. Thirty-three participants were in the DM group, 92 in the HTN group and 68 in the DM/HTN group.

The participants in the DM group were younger, had lower body mass index (BMI), WC, waist–hip ratio and BP, shorter time since diagnosis and more frequently a family history of DM than the two other groups (Table 1). In addition, insulin was used more frequently as diabetes medication in the DM group than in the DM/HTN group (< 0.05). Microalbuminuria was present in 12.1%, 19.6% and 29.4% of the participants in the DM group, HTN group and DM/HTN group, respectively (P = 0.11) (Figure 1). Macroalbuminuria was found in 0.0%, 3.3% and 13.2% of the DM group, HTN group and DM/HTN group, respectively (P = 0.014). Further, urine albumin (mg/ml) (P = 0.014) and ACR (mg/mmol) (P = 0.0006) differed between the three groups.

Table 1. Characteristics and medication of the three groups: Diabetes Mellitus (DM) only, Hypertension (HTN) only and combined DM and HTN (DM + HTN)
VariableDiabetes mellitus P-value
DMDM + HTNHTN
n = 33n = 68n = 92
  1. Data are medians (interquartile range), and categorical variables are %. ACE: angiotensin-converting enzyme; BP, blood pressure; Pulse pressure (PP) = Systolic BP – Diastolic BP; Mean arterial pressure (MAP) = DBP + (1/3)*PP. In the DM + HTN group, the time since the disease (DM or HTN) diagnosed first was used as ‘time since diagnosis’.

Sex (% men)66.7% (22/33)42.7% (29/68)22.8% (21/92)<0.0001
Age (years)41 (26–52)60 (52–69)63 (53–69)<0.0001
BMI (kg/m2)22.2 (19.6–25.0)28.0 (25.0–30.3)24.4 (21.4–29.9)<0.0001
Waist circumference (cm)77.0 (71.0–92.0)99.5 (89.7–106.0)90.0 (78.1–104.2)<0.0001
Waisthip ratio0.84 (0.80–0.92)0.93 (0.89–0.98)0.89 (0.83–0.94)<0.0001
Systolic BP (mmHg)120 (107–128)149 (133–160)144 (129–163)<0.0001
Diastolic BP (mmHg)78 (72–85)90 (86–97)91 (85–99)<0.0001
Pulse pressure (mmHg)39 (32–46)55 (47–65)52 (41–66)<0.0001
MAP (mmHg)91 (82–99)109 (102–116)108 (101–119)<0.0001
HbA1c (%)8.3 (6.3–10.3)7.4 (6.5–9.0)5.8 (5.5–6.0)<0.0001
Random capillary glucose (mmol/l)6.4 (4.7–10.7)8.5 (6.1–12.1)4.9 (4.2–5.6)<0.0001
Time since diagnosis (years)3 (1–5)5 (3–11)4 (1–10)0.015
Family history (DM)36.4% (12/33)22.4% (15/68)2.2% (2/92)<0.0001
Family history (HTN)9.1% (3/33)20.9% (14/68)41.3% (38/92)0.0005
Smoking0% (0/33)1.5% (1/68)2.2% (2/92)0.69
Known Comorbidity
Congestive heart failure0.0% (0/33)1.5% (1/68)6.5% (6/92)0.11
Chronic obstructive lung disease0.0% (0/33)0.0% (0/68)2.2% (2/92)0.33
Previously TB treated6.1% (2/33)1.5% (1/68)5.4% (5/92)0.38
Previously HIV tested63.6% (21/33)45.6% (31/68)45.7% (42/92)0.17
HIV positive3.0% (1/33)2.9% (2/68)2.2% (2/92)0.93
HIV treatment3.0% (1/33)2.9% (2/68)1.1% (1/92)0.39
Medication
Diabetes medication100% (33/33)83.8% (57/68)0.015
Insulin60.6% (20/33)16.2% (11/68)<0.0001
Metformin45.5% (15/33)69.1% (47/68)0.022
Sulphonylureas33.3% (11/33)42.7% (29/68)0.37
≥2 diabetes medication39.4% (13/33)44.1% (30/68)0.65
Antihypertensive medication94.1% (64/68)92.4% (85/92)0.77
ACE-inhibitors76.5% (52/68)28.3% (26/92)<0.0001
Diuretics42.7% (29/68)78.3% (72/92)<0.0001
Beta-blockers20.6% (14/68)48.9% (45/92)0.0002
Calcium-channel-blockers23.5% (16/68)17.4% (16/92)0.37
Methyldopa4.4% (3/68)18.5% (17/92)0.0067
≥2 antihypertensive medication52.9% (36/68)68.5% (63/92)0.046
Figure 1.

Albuminuria in the three groups: Diabetes mellitus (DM) only, Hypertension (HTN) only and combined DM and HTN (DM + HTN). Variables are in %, except urine albumin which is median. ACR, Albumin-creatinine ratio.

Discussion

To our knowledge, this study is the first to present an assessment of albuminuria among patients with DM or HTN in rural SSA. The nature of this study was that of a survey as it was hospital-based and drew on a small number of participants who were all pre-diagnosed with DM or HTN. Information on comorbidity was limited, and many of the participants had undetermined HIV status; albuminuria could therefore have various underlying causes including HIV-associated nephropathy (Han et al. 2006). Nevertheless, we consider this survey an important preliminary study as albuminuria in patients with DM or HTN in rural SSA is poorly investigated.

The participants in the DM group were younger, less obese, non-hypertensive and more frequently treated with insulin than participants in the DM/HTN group. Thus, a number of participants in the DM group may have had type 1 DM, latent autoimmune diabetes of adults or African subtypes of DM (Gill et al. 2009), whereas the DM/HTN group in general had characteristics of type 2 DM. Hence, the dispersion of albuminuria between the groups could be explained by the fact that albuminuria is usually more prevalent in patients with type 2 DM than with type 1 DM (Ohta et al. 2010) and, furthermore, the BP in the HTN group and DM/HTN group was not adequately controlled. In addition, the higher frequency of macroalbuminuria in the DM/HTN group compared with the two other groups may indicate a considerably higher risk of progression to ESRD and early death (Fox et al. 2012).

Albuminuria was, in general, less frequent among the participants of the present survey than in previous studies among patients with DM or HTN in urban SSA (Busari et al. 2011; Osafo et al. 2011; Danquah et al. 2012). Danquah et al. (Danquah et al. 2012) only included patients diagnosed with type 2 DM and reported a less frequent usage of ACE-inhibitors (33%). However, their participants were fairly similar to the participants with DM in this survey in terms of age, BP and BMI. The participants in the HTN group of the present survey had better controlled BP, but were older, than adult non-diabetic Nigerians with newly diagnosed HTN (Busari et al. 2011). Further, the fact that all participants had access to free medication and treatment and the urban-versus-rural difference in lifestyle could also have contributed to the difference in results.

The cross-sectional design constituted additional limitations to the present survey in that follow up examinations and repetitive measurements of albuminuria in each participant would have been preferable, but not practicable for the actual study setting.

In conclusion, this survey is the first to present an assessment of albuminuria in rural SSA. We found a lower frequency of albuminuria than previously found in patients with DM or HTN in urban areas of SSA. Furthermore, we found that patients with both DM and HTN were more liable to have albuminuria than patients with DM only or HTN only. Prospective studies of albuminuria in SSA involving a higher number of participants and with detailed information on each participant are needed with a view to generating valid results that can be employed effectively for the benefit of the health status of SSA populations.

Acknowledgements

The authors are most grateful to all the participants and staff of St. Francis Hospital for their contributions to this work. The authors are indebted to the foundation Tove Birte Jensens Mindelegat for its financial support, to Axis Shield PoC (Oslo, Norway) for the equipment donated and to Claus Adam Jarløv (GlobalDenmark, Copenhagen, Denmark) for help in language editing the manuscript.

Funding

This work was supported by a grant from Tove Birte Jensens Mindelegat. The Afinion AS100 Analyzer and test cartridges, used to measure albuminuria and HbA1c, were donated by Axis Shield PoC (Oslo, Norway).

Duality of interest

None.

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