This paper describes the association of multiple health determinants with an important labor productivity variable (absenteeism) in an African context. The industries represented are similar to those of the formal private sector of Namibia, although the sample is not representative of the entire formal sector of the country. Agriculture is the largest industry in Namibia (15.9%), followed by employment in private households (10.9%) (not captured in this study) and retail (9.1%) which was the largest group represented by this study [23
]. Other sectors not represented in this study include public administration, education, mining and real estate. However, other important industries such as services, retail, tourism, fishing, and agriculture were included. The distribution of participants among different sectors does not reflect the proportions present in the Namibian formal sector, but does cover a large range of activities.
Namibia enacted the Labour Act in 1992, which was revised in 2007 (Act 11, 2007). Both the old and new Labour Act gives all employees (permanent and short-term contracts) a right to sick leave. The Labour Act states that during the first 12 months of employment, employees who work 5 days per week accrue 1 day of sick leave for every 5 weeks of employment. Employees that work 5 days per week are entitled to 30 working days of sick leave and those working 6 days per week can take up to 36 working days of sick leave, in a 3 year cycle. While the law may not be applied consistently everywhere, the majority of companies comply in providing paid sick leave [24
]. A medical certificate is also required for sick leave, which may act as a barrier to some seeking care given that they may have to pay out-of-pocket. In addition, employers are required to pay employees full salary benefits for the allowed sick leave. However, there are no studies published looking at employer compliance with the law and the effect on employee absenteeism in Namibia. It is possible that employees may not use sick leave if they know they will not be compensated or that there may be some threat to their position from several absences.
There are a number of reports examining absenteeism rates in Europe and the United States. These reports show average sick leave rates ranging from 5.1 days per year for employees in Europe to just over 8 days per year for employees in the United States and up to 12 days per year for public sector employees in those countries [25
]. Assuming the same rates of absenteeism in this study hold for the full year, we could expect there to be an average rate of sick leaves taken by the study participants close to 4 days per year. This calculation would put Namibian absenteeism rates in the formal sector somewhat below the estimates from the United States and Europe. Similar statistics for neighboring sub-Saharan African countries were not readily accessible. Despite much progress toward strengthening the health system, access to care for Namibians remains an area of concern. Public health facilities, which are the most accessible, are understaffed and patients may have to pay out-of-pocket [27
]. These barriers to access may also be reducing absenteeism as employees decide to continue working rather than trying to seek care.
Compared with current research on absenteeism in the workplace, this study looks at a variety of health-related determinants without focusing on any one condition. It provides some insight into the prevalence of different risk factors and conditions among workers in various industries as well as the relative impact of those factors on absenteeism. The majority of absenteeism research is focused on high-income countries [11
], and highlights the effect of particular chronic conditions on absenteeism. The findings of these studies consistently find a strong association between NCDs, their risk factors, and increased absenteeism. For most absenteeism-related studies in high-income countries, the recall period is longer and can be validated against employee records which help minimize recall bias. This level of information is not available for the current study as with many studies looking at sickness work absence in a sub-Saharan context [9
]. As a result, the true level of absenteeism in this population may be underestimated as a result of recall bias or may be subject to whether employees have access to basic care services provided by some of the employers, as with the agriculture sector [10
It is apparent from findings in Table that NCDs and their associated risk factors are affecting the working population in Namibia. This is consistent with findings from studies in high-income countries [11
]. This survey found a relatively high proportion of central obesity (18.7%) and elevated or high blood pressure (27.0%). In addition, diabetes had a significant impact on the rate of sick days although affecting a relatively low proportion of the population (1.7%). Moreover, anaemia which may be caused by a large number of conditions, including HIV, was also found to affect absenteeism. The mix of NCD and communicable disease is in line with the epidemiological transition that many low- and middle-income countries face today [28
The most significant finding of this study is the association of diabetes with absenteeism. Random blood glucose is not a rigorous test for conditions like impaired glucose tolerance or diabetes and is sensitive to whether a person has eaten recently. However, the American Diabetes Association has established that a random blood glucose measurement above 11.1 mmol/L is very likely a sign of diabetes [22
]. Therefore, although the actual diagnosis of diabetes could not be made, the current glucose results suggest that diabetes has an important impact on absenteeism and employee health.
Almost half of those who were overweight or obese also had high blood pressure readings and elevated blood glucose. This finding is compatible with other studies that have shown that the majority of people diagnosed with one non-communicable disease have co-morbidity with another [28
]. NCDs share many common risk factors and several of those are modifiable, especially through lifestyle changes. These shared factors provide an opportunity for prevention strategies centered on improving diet, physical activity, and smoking reduction. Education strategies to reduce these risks could be included in workplace wellness programs and could have an effect on both the health of employees and reducing absenteeism.
Despite showing a less significant impact on absenteeism in this study, HIV is still a significant determinant of increased sick days. In the current study it is not possible to determine reasons for sick leave or to directly relate absenteeism to HIV. It is possible that some employees missed work in order to access ART care in a location away from their workplace. Conversely, it is possible that a number of the HIV positive workers are still in the early phase of infection and therefore are not yet on ART. These people could have more frequent (short) episodes of sickness, as compared to HIV negative people or HIV positive people on ART. HIV positive workers could also have other HIV positive family members and take more frequent sick leave days to care for them.
Discovering the reasons behind diabetes- and HIV-related absenteeism may help the private sector provide services that minimize costs lost to employee sickness. For the fishing sector, prevalence of HIV appeared much higher than the average for the whole population (14.3% compared to 9.0%, respectively). Where HIV/AIDS is more prevalent in certain sectors, special attention should be given to providing adequate services such as prevention education and ART. The lower relative impact of HIV/AIDS compared to diabetes may be a result of successful intervention programs already in place among employers, including the exemplary high ART coverage achieved in Namibia [30
The impact of conditions like hepatitis B and syphilis were negligible and did not contribute to increased rates of sick days in the short-term. Prevalence estimates for hepatitis B surface antigen were below those reported for sub-Saharan Africa (> 8%) [3
]. The same was true for syphilis, which is well below average rates reported in general population surveys in Africa [3
]. Given the natural progression of these diseases in the absence of treatment, it is possible that infection could lead to long-term disability and contribute to future loss in overall productivity for companies with a large proportion of affected employees [24
The fishing, services, and wholesale sectors had significantly higher rates of sick days when compared to the largest sector in this study, retail, even after controlling for other factors. The prevalence of HIV and diabetes were some of the highest in these sectors as well, which may indicate causal relationships. Conversely, the agricultural sector had significantly less absenteeism, perhaps because a number of farms in Namibia provide health-related services on site to their employees [20
All of the above results are possibly subject to a bias toward workers who are fit enough to attend work on the day of the screening. If this is the case, the effects reported here are an underestimate of the true impact of these and other health factors on sick days for workers in Namibia.
Because this is a cross-sectional survey, it is impossible to determine causation and only associations between independent variables and the outcome (absenteeism) can be ascertained. In addition, the survey was meant as an awareness and management information exercise for companies and was not powered to detect particular associations. This increases the potential for type II statistical errors or the probability of finding a significant result when one does not actually exist. Because participation was voluntary, there may be a selection bias which would make results not applicable to the general population of employees. For the outcome variable (absenteeism), 890 people were missing data or refused to answer the question, which could bias the results as well. It could also be that HIV positive people preferentially declined to participate in the HIV test. No particular adjustments were made for this missing data as this is a cross-sectional survey and missing data were not found to be systematically distributed throughout the sample of industries. None of the variables had a greater than 5% proportion of missing data. While this survey collected information on those who refused to learn their results, it did not provide information on those who refused to have the test done at all.
Finally, it should be stated that the primary outcome variable (sick days) was not verified against employer records and is subject to recall bias as with any self-reported information. This bias was minimized by using a relatively short recall period of 90 days. Therefore, results cannot be extrapolated to longer time periods of observation. In addition, an important factor that could influence results, are the companies' policies regarding sick leave. These were not reviewed in the current study, but more liberal leave policies might result in higher reported absenteeism. There is a risk of underreporting of absenteeism due to cultural or workplace pressure which is not reflected in the findings. We did not review the workplace policies of each of the companies for this study, which would help to expand on this point, as it was beyond the capacity of this analysis to do so. However, this would be an important aspect to consider in the future.
There is no information available on expected absentee rates for employees in the Namibian formal sector which makes comparison of these results to a baseline impossible. However, the findings of this study may help to prioritize areas of intervention for health of employees including risk factors related to NCDs and HIV.