what is the research question of the following paper? Make your response as short as possible.
        
Title: Prevalence and incidence of pulmonary hypertension among HIV-infected people in Africa: a systematic review and meta-analysis
Asbtract:   Objective  Patients infected with HIV have a direly increased risk of developing pulmonary hypertension (PH), and of dying from the condition. While Africa carries the greatest burden of HIV infection worldwide, there is unclear data summarising the epidemiology of PH among HIV-infected people in this region. Our objective was to determine the prevalence and incidence of PH among HIV-infected people living across Africa.    Design  A systematic review and meta-analysis.    Participants  HIV-infected African people residing in Africa.    Outcome  Prevalence and incidence of PH diagnosed through echocardiography or right heart catheterisation.    Data sources  Articles published in PubMed/MEDLINE, EMBASE, African Journals Online and African Index Medicus between 1 January 1980 and 30 June 2016, without any language restriction.    Results  Overall, 121 studies were screened; 3 were included in this review: 1 from Southern Africa (South Africa), 1 from Eastern Africa (Tanzania) and 1 from Central Africa (Cameroon). These studies included HIV-infected adult patients selected based on presentation with cardiovascular symptoms. No study reported PH incidence or PH incidence/prevalence among children and adolescents. The quality assessment yielded moderate risk of bias. Ages of participants ranged between 18 and 78 years, and the proportion of females varied between 52.3% and 68.8%. The prevalence of PH in the pooled sample of 664 patients was 14% (95% CI 6%–23%).    Limitations  Only 3 studies were found eligible from 3 regions of the African continent.    Conclusions  The prevalence of PH among HIV-infected people in Africa seems very high. Further studies are urgently warranted to determine the incidence of HIV-induced PH, which must include all subregions of Africa.    Trial registration number  Review registration number PROSPERO CRD42016033863.   Provide two versions of response separated with exactly 6 asterisk symbols: ******.
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